Method and apparatus for using harq in wireless communications

ABSTRACT

Sidelink downlink control information (SL DCI) associated with transmission of one or more sidelink signals may be communicated. A wireless user device may transmit, based on the SL DCI and to one or more second wireless user devices, the one or more sidelink signals via a first quantity of sidelink channel resources. The wireless user device may receive first sidelink HARQ feedback information responsive to the one or more sidelink signals. The wireless user device may determine, based on a sidelink HARQ feedback timing, a time interval to transmit the first sidelink HARQ feedback information. The wireless user device may determine, based on the first quantity, a sidelink HARQ codebook. The wireless user device may transmit, during the time interval, based on the sidelink HARQ codebook, and to the base station, an uplink signal indicating the first sidelink HARQ feedback information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of Korean PatentApplication Nos. 10-2019-0100509, filed on Aug. 16, 2019, and10-2020-0018609, filed on Feb. 14, 2020, which are hereby incorporatedby reference in their entirety.

BACKGROUND 1. Field

The present disclosure may provide a method and apparatus for wirelesscommunications. One or more device may determine a Hybrid AutomaticRepeat Request (HARQ) codebook in wireless communications, such as newradio (NR) vehicle-to-everything (V2X) communications and any otherwireless communications.

2. Discussion of the Background

International Mobile Telecommunication (IMT) framework and standard havebeen developed by the International Telecommunication Union (ITU). Also,continuous discussion for 5-th generation (5G) communication is ongoingthrough a program called “IMT for 2020 and beyond”.

To satisfy the requirements requested by “IMT for 2020 and beyond”,various proposals have been made to support various numerologies about atime-frequency resource unit standard by considering various scenarios,service requirements, and potential system compatibility in a 3-rdGeneration Partnership Project (3GPP) new radio (NR) system.

Vehicle-to-everything (V2X) communication may include a communicationmethod of exchanging or sharing road infrastructures during driving andinformation, such as traffic conditions, through communication withother vehicles. V2X may include, for example, vehicle-to-vehicle (V2V),which may refer to long term evolution (LTE)-based communication betweenvehicles, vehicle-to-pedestrian (V2P), which may refer to LTE-basedcommunication between a vehicle and a user equipment (UE) carried by auser, and vehicle-to-infrastructure/network (V2I/N), which may refer toLTE-based communication between a vehicle and a roadside unit(RSU)/network. The RSU may be a transportation infrastructure entityconfigured by a base station or a fixed terminal, such as, an entitythat transmits a speed notification to a vehicle.

Low latency and high reliability may need to be secured for V2Xcommunication services. To secure low latency and high reliability inV2X communication services, various examples including determining aHARQ feedback transmission timing in the case of transmitting HARQfeedback information in V2X communication will be described herein.

SUMMARY

A wireless user device (e.g., transmitting user equipment (Tx UE)) mayreport sidelink HARQ feedback information to a base station (e.g., forV2X communication services). The wireless user device may need to reportfeedback information (e.g., on a Uu link) to the base station. Thewireless user device may transmit a plurality of pieces of HARQ feedbackinformation associated with different links (e.g., Uu link/SL link) tothe base station (e.g., through the same physical resource). One or moreexample HARQ codebook determination methods will be described herein.

An aspect of the present disclosure may provide a method and apparatusfor determining a Hybrid Automatic Repeat Request (HARQ) codebook invehicle-to-everything (V2X) communication.

An aspect of the present disclosure may provide a method and apparatusfor semi-statically provide a sidelink HARQ codebook in V2Xcommunication.

An aspect of the present disclosure may provide a method and apparatusfor dynamically determining a sidelink HARQ codebook in V2Xcommunication.

A method may include transmitting, by a transmitting user equipment (TxUE), HARQ feedback information in an NR V2X system. Here, the HARQfeedback information transmitting method may include transmitting aPhysical Sideline Shared Channel (PSSCH) to at least one receiving UE(Rx UE) based on a scheduled PSSCH occasion, receiving feedbackinformation about the PSSCH transmission from the at least one Rx UE,configuring a sidelink HARQ bit through a sidelink HARQ codebookconfigured based on at least one of PSSCH/Physical Sidelink FeedbackChannel (PSFCH) occasion associated with an uplink slot, a sidelink datatransmission type within the PSSCH occasion, and an associated sidelinkHARQ report scheme, and multiplexing the configured sidelink HARQ bitand uplink HARQ bit and transmitting the same to a base station.

The base station may transmit to the wireless user device, one or moreradio resource control (RRC) signals indicating one or more parametersassociated with sidelink communication between wireless user devices.The base station may transmit sidelink downlink control information (SLDCI) comprising a first indicator field that indicates a sidelink hybridautomatic repeat request (HARQ) feedback timing. The wireless userdevice may transmit, based on the SL DCI, to one or more second wirelessuser devices, a plurality of sidelink signals via a first quantity ofsidelink channel resources. The wireless user device may receive, duringa first time interval and from the one or more second wireless userdevices, first sidelink HARQ feedback information responsive to theplurality of sidelink signals. The wireless user device may determine,based on the sidelink HARQ feedback timing and based on the first timeinterval, a second time interval to transmit the first sidelink HARQfeedback information to the base station. The wireless user device maydetermine, based on the first quantity, a sidelink HARQ codebook. Thewireless user device may transmit, during the second time interval andbased on the sidelink HARQ codebook and to the base station, an uplinksignal indicating the first sidelink HARQ feedback information.

The base station may transmit, to the wireless user device, sidelinkdownlink control information (SL DCI) associated with transmission ofone or more sidelink signals. The wireless user device may transmit,based on the SL DCI and to one or more second wireless user devices, theone or more sidelink signals via a first quantity of sidelink channelresources. The wireless user device may receive, during a first timeinterval and from the one or more second wireless user devices, firstsidelink HARQ feedback information responsive to the one or moresidelink signals. The wireless user device may determine, based on asidelink HARQ feedback timing and based on the first time interval, asecond time interval to transmit the first sidelink HARQ feedbackinformation. The wireless user device may determine, based on the firstquantity, a sidelink HARQ codebook (e.g., the size of the sidelink HARQcodebook). The wireless user device may transmit, during the second timeinterval, based on the sidelink HARQ codebook, and to the base station,an uplink signal indicating the first sidelink HARQ feedbackinformation.

The HARQ feedback information transmitting method may includetransmitting a PSSCH to at least one wireless user device (e.g., an RxUE based on a scheduled PSSCH occasion, receiving feedback informationabout the PSSCH transmission from the at least one wireless user device(e.g., the Rx UE), configuring a sidelink HARQ bit through a sidelinkHARQ codebook dynamically configured based on a Counter_Sidelinkassignment indicator (C_SAI) value, and multiplexing the configuredsidelink HARQ bit and uplink HARQ bit and transmitting the same to abase station.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example frame structure for downlink/uplinktransmission.

FIG. 2 illustrates an example of a resource grid and a resource block.

FIG. 3 illustrates an example of a system architecture.

FIG. 4 illustrates an example scenario in which sidelink communicationis performed in a wireless network.

FIG. 5 illustrates an example of a sidelink resource pool.

FIG. 6 illustrates an example of Physical Sidelink Feedback Channel(PSFCH) time resources.

FIG. 7 illustrates an example of PSFCH frequency resources.

FIG. 8 illustrates an example method for reporting sidelink HybridAutomatic Repeat Request (HARQ) feedback.

FIG. 9 illustrates an example sidelink HARQ codebook.

FIG. 10 illustrates an example sidelink scenario.

FIG. 11 illustrates an example method for reporting sidelink HARQfeedback to a base station.

FIG. 12 illustrates an example method for reporting sidelink HARQfeedback to a base station.

FIG. 13 illustrates an example method for reporting sidelink HARQfeedback to a base station.

FIG. 14 illustrates an example method for configuring a sidelink HARQcodebook.

FIG. 15 illustrates an example method for configuring a HARQ codebook byconsidering a sidelink multicarrier.

FIG. 16 is a flowchart illustrating an example method forsemi-statically determining a sidelink HARQ codebook.

FIG. 17 illustrates an example method for dynamically determining asidelink HARQ codebook.

FIG. 18 illustrates an example method for dynamically determining asidelink HARQ codebook.

FIG. 19 illustrates an example method for dynamically determining asidelink HARQ codebook by considering a sidelink multicarrier.

FIG. 20 illustrates an example method for configuring a sidelink HARQfeedback information bit.

FIG. 21 illustrates an example of dynamically determining a sidelinkHARQ codebook by considering all of a Physical Downlink Control Channel(PDCCH) monitoring occasion for a sidelink and a PDCCH monitoringoccasion for a downlink.

FIG. 22 illustrates an example of dynamically determining a sidelinkHARQ codebook if a subcarrier spacing (SCS) of an active DL bandwidthpart (BWP) differs from that of an active SL BWP.

FIG. 23 illustrates an example of dynamically determining a sidelinkHARQ codebook if an SCS of an active DL BWP differs from that of anactive SL BWP.

FIG. 24 illustrates an example of dynamically determining a sidelinkHARQ codebook if an SCS of an active DL BWP differs from that of anactive SL BWP.

FIG. 25 is a flowchart illustrating an example of dynamicallydetermining a sidelink HARQ codebook.

FIG. 26 is a diagram illustrating an example configuration of a basestation device and a terminal device.

FIG. 27 illustrates an example for a transmitting user equipment (Tx UE)that determines an SL HARQ-ACK state.

DETAILED DESCRIPTION

Various embodiments of the disclosure will be described more fullyhereinafter with reference to the accompanying drawings such that one ofordinary skill in the art to which the present disclosure pertains mayeasily implement the embodiments. However, the present disclosure may beimplemented in various forms and is not limited to the embodimentsdescribed herein.

In describing the embodiments, detailed description on knownconfigurations or functions may be omitted for clarity and conciseness.Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals are understood to referto the same elements, features, and structures.

It will be understood that when an element is referred to as being“connected to”, “coupled to”, or “accessed to” another element, it canbe directly connected, coupled, or accessed to the other element orintervening elements may be present. Also, it will be further understoodthat when an element is described to “comprise/include” or “have”another element, it specifies the presence of still another element, butdo not preclude the presence of another element uncles otherwisedescribed.

Further, the terms, such as first, second, and the like, may be usedherein to describe elements in the description herein. The terms areused to distinguish one element from another element. Thus, the terms donot limit the element, an arrangement order, a sequence or the like.Therefore, a first element in an embodiment may be referred to as asecond element in another element. Likewise, a second element in anembodiment may be referred to as a first element in another embodiment.

Herein, distinguishing elements are merely provided to clearly explainthe respective features and do not represent that the elements arenecessarily separate from each other. That is, a plurality of elementsmay be integrated into a single hardware or software unit. Also, asingle element may be distributed to a plurality of hardware or softwareunits. Therefore, unless particularly described, the integrated ordistributed embodiment is also included in the scope of the disclosure.

Herein, elements described in various embodiments may not be necessarilyessential and may be partially selectable. Therefore, an embodimentincluding a partial set of elements described in an embodiment is alsoincluded in the scope of the disclosure. Also, an embodiment thatadditionally includes another element to elements described in variousembodiments is also included in the scope of the disclosure.

Further, the description described herein is related to a wirelesscommunication network, and an operation performed in the wirelesscommunication network may be performed in a process of controlling anetwork and transmitting data in a system that controls the wirelesscommunication network (e.g., a base station), or may be performed in aprocess of transmitting or receiving a signal in a user equipmentconnected to the wireless communication network.

It is apparent that various operations performed for communication witha terminal in a network including a base station and a plurality ofnetwork nodes may be performed by the base station or by other networknodes in addition to the base station. Here, the term ‘base station(BS)’ may be interchangeably used with other terms, for example, a fixedstation, a Node B, eNodeB (eNB), gNodeB (gNB), and an access point (AP).Also, the term ‘terminal’ may be interchangeably used with other terms,for example, user equipment (UE), a mobile station (MS), a mobilesubscriber station (MSS), a subscriber station (SS), and a non-APstation (non-AP STA).

Herein, transmitting or receiving a channel includes a meaning oftransmitting or receiving information or a signal through thecorresponding channel. For example, transmitting a control channelindicates transmitting control information or a signal through thecontrol channel. Likewise, transmitting a data channel indicatestransmitting data information or a signal through the data channel.

In the following description, although the term “new radio (NR) system”is used to distinguish a system according to various examples of thepresent disclosure from the existing system, the scope of the presentdisclosure is not limited thereto. Also, the term “NR system” usedherein is used as an example of a wireless communication system capableof supporting various subcarrier spacings (SCSs). However, the term “NRsystem” itself is not limited to the wireless communication system thatsupports the plurality of SCSs.

FIG. 1 illustrates an example of an NR frame structure and a numerologyaccording to an embodiment of the present disclosure.

In NR, a basic unit of a time domain may be T_(c)=1/(Δf_(max)·N_(f).Here, Δf_(max)=480℠10³ and N_(f)=4096. Also, κ=T_(s)/T_(c)=64 may be aconstant about a multiple relationship between an NR time unit and anLTE time unit. In LTE, T_(s)=1/(Δf_(ref)·N_(f,ref)), Δf_(ref)=15·10³ Hz,and N_(f,ref)=2048 may be defined as a reference time unit.

Frame Structure

Referring to FIG. 1, a time structure of a frame for a downlink/uplink(DL/UL) transmission may include T_(f)(Δf_(max)N_(f)/100)·T_(s)=10 ms.Here, a single frame may include 10 subframes corresponding toT_(sf)=(Δf_(max)N_(f)/1000)·T_(s)=1 ms. A number of consecutiveorthogonal frequency division multiplexing (OFDM) symbols per subframemay be N_(symb) ^(subframe,μ)=N_(symb) ^(slot)N_(slot) ^(subframe,μ).Also, each frame may be divided into two half frames and the half framesmay include 0˜4 subframes and 5˜9 subframes. Here, half frame 1 mayinclude 0˜4 subframes and half frame 2 may include 5˜9 subframes.

Here, a transmission timing of uplink transmission frame i is determinedbased on a downlink reception timing at a UE according to the followingEquation 1.

In Equation 1, N_(TA,offset) denotes a TA offset value occurring due toa duplex mode difference and the like. Basically, in a frequencydivision duplex (FDD), N_(TA,offset)=0. In a time division duplex (TDD),N_(TA,offset) may be defined as a fixed value by considering a marginfor a DL-UL switching time.

T _(TA)=(N _(TA) +N _(TA,offset))T _(c)

FIG. 2 illustrates an example of a resource grid and a resource block.

Referring to FIG. 2, a resource element within a resource grid may beindexed based on each subcarrier spacing. Here, a single resource gridmay be generated for each antenna port and for each subcarrier spacing.Uplink/downlink transmission and reception may be performed based on acorresponding resource grid.

A single resource block may be configured on a frequency domain using 12resource elements and may configure an index n_(PRB) for a singleresource block every 12 resource elements as represented by thefollowing Equation 2. An index of the resource block may be used in aspecific frequency band or system bandwidth.

$\begin{matrix}{n_{PRB} = \lfloor \frac{k}{N_{sc}^{RB}} \rfloor} & \lbrack {{Equation}\mspace{14mu} 2} \rbrack\end{matrix}$

Numerologies

Numerologies may be variously configured to meet various services andrequirements of the NR system. Also, referring to the following Table 1,the numerologies may be defined based on an SCS, a cyclic prefix (CP)length, and a number of OFDM symbols per slot, which are used in an OFDMsystem. The aforementioned values may be provided to a UE through upperlayer parameters, DL-BWP-mu and DL-BWP-cp (DL) and UL-BWP-mu andUL-BWP-cp (UL).

Also, for example, referring to the following Table 1, if μ=2 and SCS=60kHz, a normal CP and an extended CP may be applied. In other bands, onlythe normal CP may be applied.

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

Here, a normal slot may be defined as a basic time unit used to transmita single piece of data and control information in the NR system. Alength of the normal slot may basically include 14 OFDM symbols. Also,dissimilar to a slot, a subframe may have an absolute time lengthcorresponding to 1 ms in the NR system and may be used as a referencetime for a length of another time section. Here, for coexistence andbackward compatibility of the LTE and the NR system, a time section,such as an LTE subframe, may be required for an NR standard.

For example, in the LTE, data may be transmitted based on a transmissiontime interval (TTI) that is a unit time. The TTI may include at leastone subframe unit. Here, even in the LTE, a single subframe may be setto 1 ms and may include 14 OFDM symbols (or 12 OFDM symbols).

Also, in the NR system, a non-slot may be defined. The non-slot mayrefer to a slot having a number of symbols less by at least one symbolthan that of the normal slot. For example, in the case of providing alow latency such as an Ultra-Reliable and Low Latency Communications(URLLC) service, a latency may decrease through the non-slot having thenumber of slots less than that of the normal slot. Here, the number ofOFDM symbols included in the non-slot may be determined based on afrequency range. For example, a non-slot with 1 OFDM symbol length maybe considered in the frequency range of 6 GHz or more. As anotherexample, a number of symbols used to define the non-slot may include atleast two OFDM symbols. Here, the range of the number of OFDM symbolsincluded in the non-slot may be configured with a length of a mini slotup to (normal slot length)−1. Here, although the number of OFDM symbolsmay be limited to 2, 4, or 7 as a non-slot standard, it is provided asan example only.

Also, for example, an SCS corresponding to μ=1 and 2 may be used in theunlicensed band of 6 GHz or less and an SCS corresponding to μ=3 and 4may be used in the unlicensed band above 6 GHz. Here, for example, if=4, it may be used only exclusive for a synchronization signal block(SSB), which is described below. However, it is provided as an exampleonly and the present disclosure is not limited thereto.

Also, Table 2 shows a number N_(slot) ^(symb,μ) of OFDM symbols per slotfor each SCS setting. Table 2 shows a number of OFDM symbols per slotaccording to each SCS value, a number of slots per frame, and a numberof slots per subframe, as provided by Table 1. Here, in Table 2, thevalues are based on the normal slot having 14 OFDM symbols.

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

Also, as described above, if μ=2 and SCS=60 kHz, the extended CP may beapplied. In Table 3, in the case of the extended CP, each value may beindicated based on the normal slot of which the number of OFDM symbolsper slot N_(slot) ^(symb,μ) is 12. Here, Table 3 shows the number ofsymbols per slot, the number of slots per frame, and the number of slotsper subframe in the case of the extended CP that follows the SCS of 60kHz.

TABLE 3 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

Hereinafter, a structure of an SS/Physical Broadcast Channel (PBCH)block in the NR system and an initial cell access structure in the NRsystem are described.

Here, an NR base station (i.e., gNB) may periodically transmit signalsand channels as shown in the following Table 4 to allow an initial cellselection of UEs in a cell.

TABLE 4 SS/PBCH block (i.e., SSB) SIB1 (System Information Block 1)Other SIBs

For example, the SS/PBCH block may be the aforementioned SSB. Here, evenin the NR system, a UE may need to receive a broadcast channel forforwarding a synchronization signal and important system informationtransmitted from a corresponding wireless access system to perform aninitial wireless access. To this end, the UE may check receivingsensitivity of a synchronization signal to discover an optical cellpresent in a most excellent channel environment. The UE may perform afrequency/time synchronization and cell identification operation forperforming an initial access to an optimal channel among one or morechannels in a specific frequency band operated based on the checkedreceiving sensitivity. The UE may verify a boundary of OFDM symboltiming through the aforementioned operation and then may initiate a PBCHdemodulation in the same SSB.

Here, the UE may receive a PBCH demodulation reference signal (DMRS) andmay perform a PBCH demodulation. Also, the UE may acquire 3-leastsignificant bit (LSB) information from SSB index information bitsthrough the PBCH DMRS. The UE may acquire information included in a PBCHpayload by performing the PBCH demodulation. The UE may perform aprocedure of demodulating SIB 1 based on the information acquiredthrough the PBCH.

For example, in the NR system, the UE may receive remaining systeminformation (RMSI) through a broadcast signal or channel as systeminformation not transmitted from the PBCH. Also, the UE may receiveother system information (OSI) and a paging channel through a broadcastsignal or channel as other additional system information.

The UE may access a base station through a random access channel (RACH)process and then perform a mobility management.

Also, for example, when the UE receives an SSB, the UE needs to set anSSB composition and an SS burst set composition.

NR V2X Service

In association with a vehicle-to-everything (V2X) service, the existingV2X service (e.g., LTE Rel-14 V2X) may support a set of basicrequirements for V2X services. Here, the requirements are designedbasically in sufficient consideration of a road safety service.Therefore, V2X UEs may exchange autonomous status information through asidelink and may exchange the information with infrastructure nodesand/or pedestrians.

Meanwhile, in a further evolved service (e.g., LTE Rel-15) as the V2Xservice, new features are introduced by considering a carrieraggregation in a sidelink, a high order modulation, a latency reduction,a transmit (Tx) diversity, and feasibility for sTTI. Coexistence withV2X UEs (the same resource pool) is required based on the aforementioneddescription, and the services are provided based on LTE.

For example, technical features may be classified largely based on fourcategories as represented by the following Table 5 by considering usecases for supporting a new V2X service as system aspect (SA) 1. Here, inTable 5, “Vehicles Platooning” may be technology that enables aplurality of vehicles to dynamically form a group and similarly operate.Also, “Extended Sensors” may be technology that enables exchange of datagathered from sensors or video images. Also, “Advanced Driving” may betechnology that enables a vehicle to drive based on semi-automation orfull-automation. Also, “Remote Driving” may be technology for remotelycontrolling a vehicle and technology for providing an application. Basedthereon, further description related thereto may be given by thefollowing Table 5.

TABLE 5 Vehicles Platooning Vehicles Platooning enables the vehicles todynamically form a platoon travelling together. All the vehicles in theplatoon obtain information from the leading vehicle to manage thisplatoon. This information allows the vehicles to drive closer thannormal in a coordinated manner, going to the same direction andtravelling together. Extended Sensor Extended Sensor enables theexchange of raw or processed data gathered through local sensors or livevideo images among vehicles, road site units, devices of pedestrian andV2X application servers. The vehicles can increase the perception oftheir environment beyond of what their own sensors can detect and have amore broad and holistic view of the local situation. High data rate isone of the key characteristics. Advanced Driving Advanced Drivingenables semi-automated or full-automated driving. Each vehicle and/orRSU shares its own perception data obtained from its local sensors withvehicles in proximity and that allows vehicles to synchronize andcoordinate their trajectories or maneuvers. Each vehicle shares itsdriving intention with vehicles in proximity too. Remote Driving RemoteDriving enables a remote driver or a V2X application to operate a remotevehicle for those passengers who cannot drive by themselves or remotevehicles located in dangerous environments. For a case where variationis limited and routes are predictable, such as public transportation,driving based on cloud computing can be used. High reliability and lowlatency are the main requirements.

Also, the above SA1 may consider all of LTE and NR as enhanced V2X(eV2X) support technology for supporting the new V2X service. Forexample, an NR V2X system may be a first V2X system. Also, an LTE V2Xsystem may be a second V2X system. That is, the NR V2X system and theLTE V2X system may be different V2X systems. In the following,description is made based on a method of satisfying low latency and highreliability required in an NR sidelink based on the NR V2X system. Here,even in the LTE V2X system, the same or similar composition may beexpanded and thereby apply. However, it is provided as an example onlyand the present disclosure is not limited thereto. That is, even in theLTE V2X system, the present disclosure may apply to an interactableportion and is not limited to the following embodiment. Here, forexample, NR V2X capability may not be limited to essentially supportonly V2X services and V2X RaT to be used may be selected.

NR Sidelink

An NR sidelink may be used for the aforementioned NR V2X service. Here,for example, an NR sidelink frequency may consider FR1 that is afrequency of 6 GHz or less and FR2 (i.e., up to 52.6 GHz) that is afrequency over 6 GHz. Also, for example, the NR sidelink frequency mayconsider all of unlicensed ITS bands and licensed ITS bands. That is, asdescribed above, a common design method for supporting the respectivefrequency bands may be required. To this end, an NR sidelink design thatconsiders an NR system may be required. For example, similar to an NRstandard design, although it is not beam-based, even an omni-directionalTx/Rx may basically require the NR sidelink design capable of supportingbeam-based transmission and reception. However, it is provided as anexample only.

Also, for example, a physical channel for NR V2X sidelink may be set.For example, an NR Physical Sidelink Shared Channel (PSSCH) may be adata channel for NR sidelink as a physical channel. Also, for example,an NR Physical Sidelink Control Channel (PSCCH) may be a control channelfor NR sidelink as a physical channel. Here, scheduling information forthe data channel of the NR sidelink and control information may beforwarded through the NR PSCCH. For example, Sidelink ControlInformation (SCI) may be transmitted based on a format that definesfields about control information associated with scheduling of the NRsidelink data channel and control information transmitted through the NRPSCCH may be transmitted based on an SCI format.

Also, for example, an NR Physical Sidelink Feedback Channel (PSFCH) maybe defined. Here, the NR PSFCH may be an NR Hybrid Automatic RepeatRequest (HARQ) feedback channel as a physical channel. Here, HARQ-ACKfeedback information, Channel Status Information (CSI), and otherinformation corresponding to the NR sidelink data channel may beforwarded through the NR PSFCH. In detail, Sidelink Feedback ControlInformation (SFCI) including feedback information may be forwardedthrough the NR PSFCH. Here, SFCI may include information about at leastone of HARQ-ACK, channel quality information (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), reference signal received power(RSRP), reference signal received quality (RSRQ), path-gain/pathloss, ascheduling request indicator (RSI), contention resolution identity(CRI), an interference condition, a vehicle motion, and the like.However, it is provided as an example only and the present disclosure isnot limited thereto. Here, for example, the NR PSFCH is furtherdescribed.

NR V2X QoS Requirements

NR V2X QoS requirements may be a higher level than existing V2X (e.g.,LTE V2X) requirements into consideration of a service of the above Table5. For example, delay may be set within 3 ms to 100 ms based on thefollowing Table 6. Also, reliability may be set between 90% and 99.999%.Also, a data rate may be required up to 1 Gbps.

TABLE 6 Delay: [3, 100 ms] Reliability: [90%, 99.999%] Data rate: up to1 Gbps

That is, as described above, QoS requirements capable of meeting lowlatency and high reliability may be required into consideration of a V2Xservice. Here, for example, access stratum (AS) level QoS management maybe required to meet the QoS requirements. Also, for example, HARQ andCSI may be required into consideration of link adaptation to meet theQoS requirements. Also, for example, maximum bandwidth (max. BW)capability may differ for each NR V2X UE. That is, AS level informationneeds to be exchanged between UEs based on the aforementioneddescription. For example, the AS level information may include at leastone of UE capability, QoS related information, radio bearerconfiguration, and physical layer configuration. Also, for example, theAS level information may further include other information. However, itis provided as an example only and the present disclosure is not limitedthereto.

The following Table 7 may show the respective terms applied herein.However, it is provided as an example only and the present disclosure isnot limited thereto.

TABLE 7 UMTS (Universal Mobile Telecommunications System): refers to 3rdGeneration (3G) mobile communication technology based on Global Systemfor Mobile Communication (GSM), developed by 3GPP EPS (Evolved PacketSystem): refers to a network system that includes an Evolved Packet Core(EPC) that is a packed switched (PS) core network based on an Internetprotocol (IP) and an access network such as LTE/Universal TerrestrialRadio Access Network (UTRAN). A network evolved from Universal MobileTelephone System (UMTS). NodeB: refers to a base station of GERAN/UTRANand is installed outdoors and has coverage of macro cell scale. eNodeB:refers to a base station of E-UTRAN and is installed outdoors and hascoverage of macro cell scale. gNodeB: refers to a base station of NR andis installed outdoors and has coverage of macro cell scale. UE (UserEquipment): refers to a user equipment. The UE may also beinterchangeably used with terms, terminal, mobile equipment (ME), mobilestation (MS), and the like. Also, the UE may be a portable device, suchas a laptop computer, a mobile phone, a personal digital assistant(PDA), a smartphone, a multimedia device, etc. The term “UE” or“terminal” in Machine Type Communications (MTC) related content mayrefer to an MTC device. RAN (Radio Access Network): refers to a unitthat includes NodeB, eNodeB, and gNodeB, and a radio network controller(RNC) for controlling the same in a 3GPP network, and is present betweenUEs and provides a connectivity to a core network. NG-RAN (NextGeneration Radio Access Network): refers to NG-eNB (E-UTRA UP/CPprotocol) and gNB (NR UP/CP protocol) base station nodes connected to5GC (5G Core NW) based on an NG interface in a 3GPP network. Xninterface: refers to an interface for interconnection between NG-eNB andgNB. PLMN (Public Land Mobile Network): refers to a network configuredto provide a mobile communication service to individuals, and may beconfigured for each operator. Proximity service (or ProSe Service orProximity based Service): refers to a service that enables discovery anddirect communication between physically proximate apparatuses,communication through a base station, or communication through a thirdapparatus. Here, user plane data is exchanged through a direct data pathwithout going through a 3GPP core network (e.g., EPC). LTE SFN (SystemFrame Number): refers to a frame index for time domain reference of LTE.NR SFN (System Frame Number): refers to a frame index for time domainreference of NR. NR DFN (Direct Frame Number): refers to a frame indexfor time domain reference of an NR sidelink

NR Sidelink Design

Hereinafter, an NR V2X sidelink design method that meets requirementsfor the aforementioned evolved V2X (i.e., eV2X) services will bedescribed.

In more detail, a synchronization procedure and method required to forma wireless link for an NR sidelink are further described. For example,as described above, in NR sidelink design, FR1 and FR2 (i.e., up to 52.6GHz) may be considered as NR sidelink frequencies and unlicensed ITSbands and licensed ITS bands may be considered as frequency band andrange in which an NR system operates. Also, for example, theavailability of an LTE (NG-eNB)/NR Uu link that is a 3GPP NG-RAN ofTable 7 may be considered in the NR sidelink design.

Also, for example, a design for eV2X synchronization informationforwarding and signal transmission/reception to meet higher requirementsfrom the evolved V2X services may be considered. Here, a frequency forNR V2X sidelink communication may further consider at least one ofelements of the following Table 8 based on the following technologiesrequired in the new system, which differs from the existing system(e.g., LTE). That is, there is a need to meet new V2X servicerequirements by applying an NR V2X sidelink based on NR radio accesstechnology, particularly, uplink transmission related technologies asshown in the following Table 8.

Also, other elements may be considered by considering the new system aswell as the following Table 8. However, it is provided as an exampleonly and the present disclosure is not limited thereto.

TABLE 8 Scalable frequency use and configuration (e.g., Bandwidth Part[BWP]) according to broad frequency band and maximum bandwidthcapability of UE Various numerologies (e.g., variable SCSs, number ofOFDM symbols per slot (or subframe)) Slot format (slot/non-slot)Beam-based transmission/reception to cope with signal attenuation in afrequency band of 6 GHz or more corresponding to a high frequency bandConfigured grant-based uplink transmission/reception to provide lowlatency

Also, as described above, for example, a signal, a basic slot structure,a physical resource, and a physical channel of NR V2X sidelink may berepresented as the following Table 9.

TABLE 9 NR PSSCH (Physical Sidelink Shared Channel) Refers to a Physicallayer NR SL data channel. NR PSCCH (Physical Sidelink Control Channel)Refers to a channel for forwarding control information as well asscheduling information of an NR SL data channel as a physical layer NRSL control channel. NR SLSS/PSBCH (Sidelink SynchronizationSignal/Physical Sidelink Broadcast Channel) block Refers to asynchronization and broadcast channel block in which an NR SLsynchronization signal and a broadcast channel are transmitted on asingle continuous time in a physical layer. Periodical transmission isperformed based on a set of at least one block index to supportbeam-based transmission on an NR frequency band. The synchronizationsignal includes a PSSS and a SSSS and a sequence for the correspondingsignal is generated based on at least one SLSSID value. The PSBCH istransmitted with SLSS for the purpose of forwarding system informationrequired to perform V2X SL communication. Likewise, periodictransmission is performed based on a set of SLSS/PSBCH block indices tosupport beam-based transmission.

Here, for example, FIG. 3 illustrates an example of a basic networkarchitecture composition considered for an NR V2X sidelink.

For example, referring to FIG. 3, NG interfaces may be set between nodes310-1 and 310-2 of a 5-th generation core (5GC NW) and nodes 320-1,320-2, 330-1, and 330-2 of an NG-RAN. Also, Xn interfaces may be setbetween the nodes 320-1, 320-2, 330-1, and 330-2 of the NG-RAN. Here, inthe above architecture, corresponding nodes may be interconnectedthrough the corresponding Xn interface based on gNB (NR UP/CP protocol)corresponding to the nodes 320-1 and 320-2 and ng-eNB (E-UTRA UP/CPprotocol) corresponding to the nodes 330-1 and 330-2, which constitutethe NG-RAN. Also, as described above, in the 5GC, corresponding nodesmay be interconnected through a corresponding NG interface. Here, forexample, in the above architecture, all of an LTE sidelink UE and an NRsidelink UE may be controlled by the NG-RAN (i.e., LTE Uu and NR Uu)based on the gNBs and ng-eNBs. Therefore, when transmittingsynchronization information, the NR sidelink UE may receivesynchronization information from the LTE Uu or NR Uu link, and maytransmit NR sidelink synchronization information (e.g., SLsynchronization signal/SL Physical Broadcast Channel (PBCH)) based onthe received synchronization information. However, it is provided as anexample only and the present disclosure is not limited thereto. That is,the NR sidelink UE may also acquire the synchronization informationthrough the LTE Uu link as well as the NR Uu link.

Meanwhile, with respect to V2X sidelink communication, V2X sidelink UEsmay perform the V2X sidelink communication. Here, predeterminedconditions need to be met such that the V2X sidelink UEs may start thecommunication. The conditions may be represented by the following Table10. That is, a V2X sidelink UE may perform V2X sidelink communication ina Radio Resource Control (RRC) idle mode, inactive mode, or connectedmode. Also, V2X sidelink UEs that perform the V2X sidelink communicationneed to be registered on a selected cell on a using frequency or need tobelong to the same PLMN. Also, if a V2X sidelink UE is an OOC on afrequency for V2X sidelink communication, the V2X sidelink UE mayperform the V2X sidelink communication only when it is possible toperform the V2X sidelink communication based on pre-configuration.

TABLE 10 If a UE is in an RRC_IDLE or INACTIVE or CONNECTED mode in aspecific cell, If a UE is registered to a selected cell on a frequencyused for V2X SL communication or belongs to the same PLMN, If a UE is anOCC on a frequency for a V2X SL communication operation, and if a UE iscapable of performing V2X SL communication based on pre-configuration

Here, as described above, to start the V2X sidelink communication,sidelink synchronization information may be required. Therefore, the UEneeds to transmit the sidelink synchronization information. Here, a TxUE (sidelink Tx UE) may receive a configuration for transmittingsidelink synchronization information prior to transmitting correspondingsynchronization information. Here, for example, the Tx UE may receivethe configuration for transmitting the sidelink synchronizationinformation based on a system information message or an RRCreconfiguration message (in the case of an RRC CONNECTED UE) broadcastedfrom the above NG-RAN nodes. Also, for example, if an NR V2X sidelink UE(hereinafter, referred to as a UE) is absent in an NG-RAN, the UE maytransmit sidelink synchronization information based on thepre-configured information, which is described above.

Meanwhile, FIG. 4 illustrates an example of a scenario in which NR V2Xsidelink communication is performed in a 3GPP network based on theaforementioned description. Here, the NR V2X sidelink communication maybe performed on the 3GPP network (hereinafter, NG-RAN). Additionally,presence of a Global Navigation Satellite System (GNSS) signal may beconsidered.

In detail, referring to FIG. 4, each of NR V2X sidelink UEs may be an ICor an OOC based on EUTRA NG-eNB 410, may also be an IC or an OOC basedon gNB 420, and may also be an IC or an OOC based on GNSS 430. Here, NRV2X sidelink UEs may select a resource of synchronization referencebased on a position and capability of a UE. Also, for example, inaddition to the scenario of FIG. 4, scenarios shown in the followingTable 11 may be considered. It is provided as an example only and thepresent disclosure is not limited thereto.

TABLE 11 NR Uu CONNECTED/IDLE/Inactive for NR Sidelink NG-eNB UuCONNECTED/IDLE for NR Sidelink EN-DC or MR-DC for NR Sidelink

Meanwhile, in the following, an NR SCS may refer to one of an SCS valuefor NR DL SS/PBCH, an SCS value for an NR BWP (data/control channel),and a reference SCS value defined/set for comparison of NR V2X SCSvalues. As another example, the NR SCS may refer to one of an SCS valuefor NR V2X SLSS/PSBCH, an SCS value for NR V2X BWP or a resource pool(data/control channel), and a reference SCS value defined/set forcomparison of NR V2X SCS values. However, it is provided as an exampleonly and the present disclosure is not limited thereto. Also, forexample, 30 kHz SCS value may be set as a default value and used for 5.9GHz ITS spectrum. However, it is provided as an example only and thepresent disclosure is not limited thereto.

In the case of performing NR V2X sidelink communication, datatransmission may be performed based on unicast/groupcast. Here, forexample, unicast transmission may refer to transmitting a message from asingle UE to another UE, that is, one-to-one transmission. Also,broadcast transmission may refer to a scheme of transmitting a messageto all of UEs regardless of whether a service is supported at an Rx UE.That is, a single UE may transmit a message regardless of whether aplurality of Rx UEs is supporting a service. Meanwhile, a groupcasttransmission scheme may be a scheme of transmitting a message to aplurality of UEs that belongs to a group.

Here, for example, whether to activate the unicast, groupcast, orbroadcast data transmission and reception and whether to perform asession connection may be determined at an upper layer. That is,although a physical layer of a V2X UE may operate based on aninstruction that is determined in an upper layer, it is provided as anexample only and the present disclosure is not limited.

Also, for example, a V2X UE may perform corresponding transmission andreception after a session for corresponding unicast or groupcast datatransmission is formed. When a V2X UE performs transmission andreception based on the aforementioned session, physical layer parameterinformation for data transmission corresponding to unicast or groupcastmay be known in advance in the physical layer of the V2X UE. Forexample, the V2X UE may receive and recognize in advance theaforementioned information from a base station. As another example, theaforementioned information may be information preset to the V2X UE.Here, for example, unicast or multicast data transmission and receptionmay apply only to a case in which a relatively small number of V2X UEsare present around a Tx V2X UE and a session is stably maintained. Inaddition, if a session is unstable or if adjacent V2X UEs vary a lot,data transmission may be performed based on broadcast transmission.Here, it is provided as an example only and the present disclosure isnot limited thereto.

Also, for example, as described above, unicast or groupcast transmissionand reception may be determined in an application layer end as an upperlayer. Here, for example, data allocable to transmission and receptiongenerated in an application layer may be not directly mapped to a radiolayer. Here, for example, in the case of performing the unicast orgroupcast transmission and reception, a mapping relationship or aconnection establishment procedure may be required to perform datatransmission and reception on the radio layer. However, it is providedas an example only and the present disclosure is not limited thereto.

Also, for example, in the case of performing the unicast datatransmission and reception, corresponding Tx and Rx UEs may need toestablish a session by performing a procedure (e.g., a discoveryprocedure) of discovering their presence, and such session establishmentmay be performed based on various methods. Here, the sessionestablishment between the UEs may be performed with assistance of a basestation. The base station may gather position information of UEs and maydetermine whether UEs capable of performing unicast or groupcast datatransmission and reception are adjacent to each other. Here, forexample, the base station may determine whether the UEs are adjacent toeach other based on a threshold. Here, a predetermined value may be usedto determine the threshold. When the UEs in a cell are determined to beadjacent to each other, the base station may initialize a correspondingdiscovery procedure and the UEs may perform the corresponding discoveryprocedure to discover each other based on an initialization procedure.Also, the base station may determine whether an adjacent V2X SL UE ispresent by designing a new discovery channel and by periodicallytransmitting and receiving the corresponding channel. Also, the basestation may determine whether an adjacent UE is present by transmittinga corresponding discovery message on a V2X data channel. However, it isprovided as an example only and the present disclosure is not limitedthereto. That is, session establishment for unicast or groupcast datatransmission and reception may be completed based on the aforementionedprocedures. Subsequently, the upper layer may notify the physical layerof information about the session establishment and may perform aphysical layer operation, such as HARQ-ACK, CSI, and link adaptation.

At least some communications (e.g., wireless communication in accordancewith 3GPP 5G NR Release 16, or any earlier or later releases, or anyother wireless communications) may use one or more bandwidth parts(BWPs). For example, for certain transmission and reception of a signal,a frequency bandwidth to be used may not need to be as wide as abandwidth of a serving cell. The bandwidth (e.g., the bandwidth of aBWP) may be configured as a narrower bandwidth than the bandwidth of theserving cell. A frequency position of the bandwidth may be shifted. Abandwidth of an OFDM subcarrier may be changed. It may be defined as apartial set of the entire frequency bandwidth of the serving cell, whichmay be referred to as a BWP or any other terminology.

A serving cell may include one or more BWPs. One or more messages (e.g.,one or more RRC messages) configuring the BWPs of the serving cell mayinclude information about a plurality of different BWPs for a wirelessuser device (e.g., by way of signaling from a base station). The BWPs ofthe serving cell may include a pair of an uplink BWP and a downlink BWP(e.g., at all times). Composition information about a single BWP mayinclude composition information about an uplink and a downlink (e.g., atall times). A number of BWPs to be activated may be limited to a singleBWP among the plurality of BWPs or more than one BWPs may be activatedsimultaneously. If the wireless user device is capable of activating atleast one BWP, the base station may verify information about a maximumnumber of active BWPs of the wireless user device and may alsosimultaneously activate the plurality of BWPs based on the verifiedinformation. For example, if the wireless user device is configured withthe serving cell, a single BWP may be activated for the serving cell(e.g., without separate signaling from the base station). The wirelessuser device may perform access to the serving cell and the wireless userdevice may use the activated BWP (e.g., for an initial access or othertypes or random access). The initial BWP may be used (e.g., until thewireless user device receives composition information for the wirelessuser device from the base station).

If the wireless user device receives the composition information for thewireless user device (e.g., UE composition information) from the basestation, the wireless user device may be configured with a default BWP.The default bandwidth may be configured as a relatively narrow bandwidth(e.g., narrower than other BWPs). If an amount of data to be transmittedand received is small, the wireless user device may reduce batteryconsumption of the wireless user device by activating the defaultbandwidth. If the wireless user device is not configured with thedefault bandwidth, the wireless user device may use the initial BWP forthe same or similar purposes.

The activated BWP of the serving cell may be switched with another BWPdepending on one or more circumstances. This operation may be referredto as BWP switching. For a BWP switching, the wireless user device mayinactivate the currently activated BWP and may activate a new BWP. TheBWP switching operation may be performed, for example, if the wirelessuser device receives BWP switching order (e.g., through a PDCCH order)or any other BWP switching triggering event. The BWP switching operationmay be performed through a predetermined timer “bwp-InactivityTimer” asa timer for BWP inactivity. The BWP switching operation may be performedin response to starting a random access. As further described herein,one or more conditions and/or events that may cause a BWP switching willbe described. The base station may change an active BWP in the servingcell of the wireless user device depending on one or more circumstances.If the wireless user device determines to change an active BWP, the basestation may notify the wireless user device that a BWP is switched. Thenotification of the BWP switching may be indicated through a PDCCH orany other downlink signaling. The wireless user device may perform theBWP switching operation through BWP switching related information (e.g.,included in the PDCCH and/or an RRC configuration).

The timer “BWPInactivityTimer” may be configured for each serving cellor may be commonly used for a plurality of BWPs. “BWPInactivityTimer”may be a timer for inactivating the activated BWP (e.g., if the timerexpires). A timer performing the same functionality may be“BWPInactivityTimer” or any other timers. “BWPInactivityTimer” may beused for clarity of description, other timers or timer parameters mayperform the functions or operations of “BWPInactivityTimer” describedherein. If the timer (e.g., “BWPInactivityTimer”) expires, the wirelessuser device may inactivate the current activate BWP and may activate thedefault BWP. BWP switching may be performed using the default BWP or anyother BWPs. If the wireless user device is not configured with thedefault BWP, the wireless user device may switch to the initial BWP. Thewireless user device may reduce battery consumption by monitoring anarrow bandwidth through the BWP switching operation. Start and restartcondition of the timer may be set (e.g., represented by the followingTable 2). If the wireless user device needs to maintain the activatedBWP as follows, the timer may start or restart to prevent the activatedBWP from being inactivated or from being switched to another BWP. One ormore features of the BWP is further described below.

At least some communications (e.g., wireless communication in accordancewith 3 GPP 5G NR Release 16, or any earlier or later releases, or anyother wireless communications) have a wide system bandwidth configurableon a single carrier, which differs from other types of communications,such as LTE. If the NR system (or other communication systems) operatesin frequency range 2 (i.e., over 6 GHz frequency bands) in which manyfrequency bands and bandwidths thereof are available for the NR system,a system bandwidth available for the base station and a bandwidth inwhich the wireless user device actually operates may be differentlyconfigured. The system bandwidth assumed by the base station (or anetwork and/or system) and the frequency bandwidth used for the wirelessuser device to actually operate may conform to 3 GPP NR standards (orany other configurations) and may be different in view of capability ofmaximum RF bandwidth of the base station and the wireless user device,and wireless user device implementations (e.g., UE implementation) andrelated operation. Configurations of the frequency bandwidth used by thewireless user device may be provided from the base station, which maycorrespond to a BWP configuration. The BWP configuration used by thewireless user device may vary based on a mode of the wireless userdevice and a BWP configuration status. In general, bandwidth part (BWP)configuration provided from the base station to the wireless user devicethrough system information for initial cell access may be referred to asan initial active BWP, which may be used to perform a random accessprocedure.

BWPs may include an initial DL BWP. As the BWP provided from the basestation to the wireless user device through system information for theinitial cell access of the wireless user device, a bandwidth about aninitial DL active BWP for System Information Block (SIB1) transmissionand related Control Resource Set (CORESET) configuration information maybe provided through an SS/PBCH block reception. The initial DL activeBWP may be initial UE bandwidth information for receiving SIB1information.

BWPs may include an initial UL BWP. Within the SIB1, configurationinformation for performing a random access procedure may be provided andinformation about an initial uplink bandwidth (e.g., an initial UEuplink bandwidth) for some message transmission/reception within therandom access procedure. For example, initial UL active BWP information(e.g., a frequency position, a bandwidth, numerology, etc.) may beprovided.

Through this information, an uplink PUSCH message of a random accessprocedure (e.g., msg.3 or an uplink RACH message of a four-step randomaccess procedure) may be transmitted. Numerology of the initial ULactive BWP may be identical to numerology information for msg.3transmission.

PUSCH transmission (e.g., for msg.3) and PUCCH transmission for HARQfeedback transmission (e.g., for msg.4 or a downlink response message ofa four-step random access procedure) within the RACH procedure may belimited to be within the initial active UL BWP.

-   -   In an unpaired spectrum, such as TDD, an initial DL BWP and an        initial UL BWP may share the same center frequency.    -   A bandwidth of the initial active UL BWP may be generally less        than or equal to a minimum Tx bandwidth of the UE.    -   From wireless user device perspective, only a single initial        active UL BWP may be supported per cell-defined SSB.

Once the wireless user device accesses a network through theaforementioned initial cell access procedure, BWP configuration up tomaximum 4 BWPs may be provided to the wireless user device (e.g.,through wireless user device-specific RRC signaling). Only a single BWPamong the plurality of BWPs may be active and used.

The following basic configuration information may be generally includedas the BWP configuration.

-   -   Numerology    -   Frequency location (e.g., center frequency)    -   Bandwidth (e.g., number of PRBs)

PDCCH/PDSCH/PUSCH, a configured grant, an SRS transmission relatedconfiguration, and a beam failure recovery (BFR) configuration may beincluded and thereby provided to the wireless user device.

Numerology and Waveform Supported in NR V2X

Numerology and waveform supported in one or more wireless communications(e.g., NR2V2X or any other wireless communications) may be configured(e.g., represented by the following Table 12). Referring to Table. 12,the numerology for NR V2X may support a normal CP for 15 kHz, 30 kHz,and 60 kHz and an extended CP for 60 kHz for PSCCH/PSSCH and PSFCH inFR1 (e.g., frequency ranges below 6 GHz). The numerology may support anormal CP for 60 kHz and 120 kHz and an extended CP for 60 kHz forPSCCH/PSSCH and PSFCH in FR2 (e.g., frequency ranges equal to or above 6GHz). Also, the waveform for NR V2X may support only CP-OFDM withoutsupporting DFT-S-OFDM.

TABLE 12 FR 1 FR 2 PSSCH/PSCCH and Normal CP for 15 kHz, 30 kHz, 60 kHzNormal CP for 60 kHz, 120 kHz PSFCH Extended CP for 60 kHz Extended CPfor 60 kHz Waveform Supported only CP-OFDM (i.e., No support ofDFT-S-OFDM for NR SL in Rel-16

One or more resource pools may be configured for one or more wirelessuser devices (e.g., by higher layer signaling, such as an RRC message).The one or more resource pools may include one or more NR V2X resourcepools. For example, the NR V2X resource pool may include a set of timeand frequency resources available for sidelink transmission andreception (e.g., for NR V2X communication). The resource pool may be ina radio frequency bandwidth (RF BW). Only a single numerology (onedifferent numerologies) may be used in a single resource pool. Thewireless user device may be configured with at least one pool on asingle carrier. A single resource pool for PSSCH may includediscontinuous time resources, and frequency resources may includecontinuous or discontinuous Physical Resource Blocks (PRBs).

Referring to FIG. 5, part (a), a resource pool for PSSCH may includediscontinuous time resources in the NR V2X resource pool. If an NR V2Xservice is provided on a licensed carrier on which an NR Uu linkoperates, the wireless user device may be configured with the NR V2Xresource pool through a base station or a pre-configuration in additionto a physical resource for the NR Uu link. Resources 512, 514, and 515for sidelink may be discontinuously configured based on a symbol unit ora slot unit within the NR V2X resource pool. If the sidelink resourcepool is configured on the licensed carrier on which the NR Uu linkoperates, they may be multiplexed on different symbols or slots as shownin FIG. 5, part (a). A single resource pool for PSSCH may be configuredas discontinuous time resources.

Referring to FIG. 5, part (b), the resource pool for PSSCH may includecontinuous or discontinuous PRBs in the NR V2X resource pool. For Option1 of FIG. 5, part (b), each of resource pools 521, 522, and 523 forPSSCH may include continuous PRBs. For Option 2 of FIG. 5, prat (b),each of resource pools 524, 525, 526, 527, 528, and 529 for PSSCH mayinclude discontinuous PRBs. Resource pool 1 (524 and 527) may beconfigured on discontinuous frequency resources as shown in FIG. 5, part(b). The wireless user device may perform sidelink communication basedon the resource pool, and the operation is further described below.

BWPs may comprise one or more NR V2X sidelink BWPs. The NR V2X sidelinkBWP may be configured on a single sidelink carrier. The correspondingsidelink carrier may be a licensed carrier on which an NR Uu linkoperates or a C-V2X dedicated unlicensed carrier, such as an ITS band.The NR V2X sidelink BWP may be defined independently from an NR Uu BWPwithin the licensed carrier. Only a single NR V2X sidelink BWP (ormultiple NR V2X sidelink BWPs) may be configured on a single carrier.Although the aforementioned numerology configuration may includenumerology configured NR V2X sidelink BWP configuration, aspects are notlimited thereto. The wireless user device may use the NR V2X sidelinkBWP for transmission (Tx) and reception (Rx). The resource pool may beconfigured within a single sidelink BWP. The wireless user device mayassume that an active uplink BWP and a configured sidelink BWP areidentical at a specific point in time of the same carrier. Based on theaforementioned description, the wireless user device may performsidelink communication.

One or more time resources may include one or more time resources forPSFCH. PSFCH time resources may be configured (e.g., by the basestation) per a slot, per two slots, or per 4 slots in the V2X sidelinkresource pool. PSFCH time resources may be pre-configured (e.g., for thewireless user device) per a slot, per two slots, or per 4 slots in theV2X sidelink resource pool. If a wireless user device receives sidelinkdata (e.g., PSSCH), the wireless user device may perform PSFCHtransmission after a minimum time to prepare PSFCH transmission. Theminimum time may be configured by considering a processing time of thewireless user device.

Referring to FIG. 6, PSFCH time resources may be configured per 4 slotsin the resource pool. The PSFCH may be transmitted per 4 slots (or perany other number of slots). In FIG. 6, a PSFCH time resource 610 may beconfigured in slot 0 and PSFCH time resources 620 and 630 may beconfigured in slot 4 and slot 8, respectively. Other configurations maybe possible. A wireless user device (e.g., an Rx UE) may transmit HARQfeedback information to another wireless user device (e.g., the Tx UE)through a PSFCH time resource associated with a PSSCH. Referring to FIG.6, a PSSCH of slot 0, a PSSCH of slot 1, a PSSCH of slot 2, and a PSSCHof slot 3 may be associated with the PSFCH time resource 620 of slot 4.The wireless user device may transmit the PSFCH through a PSFCH timeresource (e.g., the first PSFCH time resource 620 occurring after thesidelink HARQ transmission) after a minimum time gap for sidelink HARQfeedback transmission. In FIG. 6, the wireless user device may performsidelink HARQ feedback transmission through the PSFCH time resource 620of slot 4 that is a PSFCH time resource occurring after the minimum timegap. If the minimum time gap is large, the wireless user device mayperform the sidelink feedback transmission through the PSFCH timeresource 630 of slot 8, instead of using the PSFCH time resource 620 ofslot 4. However, aspects are not limited thereto.

PSFCH resources may include frequency resources and/or code resources.In addition to time resources for the PSFCH, frequency resources mayneed to be determined. Referring to FIG. 7, a wireless user device(e.g., Tx UE) may transmit a PSCCH 710 and a PSSCH 720 to anotherwireless user device (e.g., an Rx UE). A frequency resource 730 used totransmit a PSFCH may be implicitly determined based on a frequencyresource used to transmit the PSSCH 720. The frequency resource 730 usedto transmit the PSFCH may be determined based on a starting RB (or astarting subchannel) of the frequency resource used to transmit thePSSCH 720. The frequency resource 730 used to transmit the PSFCH may bedetermined based on a lowest RB index or a lowest subchannel index inthe frequency resource used to transmit the PSSCH 720. However, aspectsare not limited thereto.

A wireless user device may perform a sidelink HARQ procedure. Whether toperform sidelink HARQ feedback may be configured (e.g., by an upperlayer, such as RRC signaling). The sidelink HARQ feedback may bedifferently performed based on a cast scheme. The sidelink HARQ feedbackmay be enabled or disabled based on a configuration (e.g., by the upperlayer) in unicast and groupcast. If a HARQ feedback-enabled wirelessuser device, based on the upper layer configuration, performs a HARQfeedback transmission for a groupcast transmission, it may be determinedwhether the corresponding wireless user device actually performs theHARQ feedback transmission for the groupcast transmission based on achannel status (e.g., RSRS), Tx-Rx distance, QoS requirements, and otherconditions. If sidelink HARQ feedback for unicast is enabled, thewireless user device (e.g., the Rx UE) may transmit HARQ-ACK/NACK toanother wireless user device (e.g., the Tx UE) depending on whether acorresponding transport block (TB) is successfully decoded.

If sidelink HARQ feedback for groupcast is enabled and a conditionregarding the actual HARQ feedback transmission status is satisfied(e.g., a condition about the Tx-Rx distance), the wireless user device(e.g., the Rx UE) may transmit only HARQ NACK to another wireless userdevice (e.g., the Tx UE). If the corresponding TB is not successfullydecoded, the wireless user device (e.g., the Rx UE) may transmit HARQNACK to another wireless user device (e.g., the Tx UE) (Option 1). Ifsidelink HARQ feedback for groupcast is enabled, a wireless user device(e.g., the Rx UE) may transmit HARQ-ACK/NACK to another wireless userdevice (e.g., the Tx UE) depending on whether the corresponding TB issuccessfully decoded (Option 2). For the groupcast, a sidelink HARQfeedback report scheme may be supported in a different manner. If awireless user device (e.g., the Rx UE) reports only HARQ NACK asgroupcast (e.g., Option 1), a wireless user device (e.g., the Rx UE) maydetermine whether to perform reporting by considering a distance fromanother wireless user device (e.g., the Tx UE). If the Tx-Rx distance isless than or equal to a required communication range, a wireless userdevice (e.g., the Rx UE) may transmit the HARQ feedback for PSSCH. Ifthe Tx-Rx distance is greater than the required communication range, awireless user device (e.g., the Rx UE) may not perform the HARQ feedbacktransmission for PSSCH.

For the groupcast, although the HARQ feedback is enabled, a wirelessuser device (e.g., the Rx UE) may not perform HARQ report based on theTx-Rx distance. A position of a wireless user device (e.g., the Tx UE)may be indicated through SCI associated with the PSSCH. A wireless userdevice (e.g., the Rx UE) may calculate the Tx-Rx distance based oninformation included in SCI and its position information and maydetermine whether to perform the HARQ feedback accordingly.

An NR V2X sidelink design that meets requirements for new evolved V2X(i.e., eV2X) services will be described based on the aforementioneddescription. A sidelink HARQ transmission method in which, if a mode 1wireless user device performs NR sidelink unicast transmission, the mode1 wireless user device may transmit sidelink HARQ information to a basestation, which will be further described. An NR sidelink frequency foran NR sidelink operation may be within FR1 (410 MHz-7.125 GHz) and FR2(24.25 GHz 52.6 GHz) and may apply to all of unlicensed ITS bands andlicensed ITS bands, and a frequency band range in which the NR systemoperates, without being limited to a specific band. The NR sidelinkfrequency may commonly apply to all of the aforementioned FR 1 and FR 2.The availability of an LTE (ng-eNB)/NR (gNB) Uu link (e.g., configuredin a 3GPP NG-RAN) may be considered for NR V2X sidelinktransmission/reception procedures. By considering the aforementionedaspects, ng-eNB or gNB on the NG-RAN may be described as the basestation. However, aspects are not limited to a specific type.

A wireless user device may repot sidelink HARQ (e.g., V2X SL HARQ) to abase station. A wireless user device (e.g., an NR V2X Tx UE) configuredwith a base station scheduling mode (i.e., mode 1) may be scheduled witha sidelink transmission resource through the base station. The mode 1wireless user device may request the base station for a transmissionresource to transmit V2X service-related data to another wireless userdevice through a sidelink. in response to the request from the wirelessuser device, the base station may schedule the sidelink transmissionresource and provide the scheduled resource to the wireless user device.The wireless user device may perform a V2X sidelink transmission usingthe scheduled resource.

A wireless user device (e.g., the V2X Tx UE) configured with a wirelessuser device auto-control mode (i.e., mode 2) may autonomously select asidelink transmission resource and may transmit data to another wirelessuser device through the selected resource. The wireless user device maybe pre-configured with a transmission resource pool to be used by thewireless user device (e.g., the V2X Tx UE). The wireless user device mayautonomously select a portion of resources to be used for actual V2Xdata transmission from among resources within the transmission resourcepool.

A wireless user device (e.g., the V2X Tx UE) may acquire SL HARQ-ACKfeedback information about the PSSCH (data channel) transmitted toanother wireless user device (e.g., the V2X Rx UE) through the sidelink,from the other wireless user device (e.g., the Rx UE) through PSFCH. Ifthe wireless user device (e.g., the Tx UE) is in a base stationscheduling mode, the wireless user device (e.g., the Tx UE) may transmitcorresponding sidelink HARQ-ACK feedback information to the base station(e.g., through an NR Uu link) to inform the base station regardingwhether to perform retransmission scheduling. The wireless user device(e.g., the Tx UE) may transmit the corresponding sidelink HARQ-ACKfeedback information to the base station (e.g., using an NR Uu uplinkchannel). The wireless user device (e.g., the Tx UE) may multiplex andthereby transmit CSI (e.g., HARQ-ACK, CQI, PMI, RI, etc.) on the NR Uulink and the sidelink HARQ feedback information through the uplinkchannel. The wireless user device (e.g., the Tx UE) may transmit onlythe corresponding sidelink HARQ-ACK feedback information to the basestation through the uplink channel. However, aspects are not limitedthereto.

Referring to FIG. 8, a wireless user device (e.g., an NR V2X Tx UE 810)corresponding to a source wireless user device may transmit a PSSCH(i.e., data) to another wireless user device (e.g., an NR V2X Rx UE 820)corresponding to a destination wireless user device through a sidelink.The wireless user device (e.g., NR V2X Tx UE 810) may receive HARQ-ACKfeedback information from another wireless user device (e.g., the NR V2XRx UE 820). If the wireless user device (e.g., the NR V2X Tx UE 810) isa mode 1 configured wireless user device and the sidelink transmissionis performed based on unicast, the wireless user device (e.g., the NRV2X Tx UE 810) may report to a base station 830 for sidelink HARQ-ACKfeedback information received from the other wireless user device (e.g.,the NR V2X Rx UE 820) through an NR Uu uplink channel.

Abase station and/or a wireless user device may communicate for one ormore HARQ codebook determinations. For example, NR HARQ codebook may bedetermined for NR sidelink HARQ report. If a wireless user device (e.g.,a Tx UE) is configured with a base station scheduling mode (hereinafter,mode 1) as a sidelink resource allocation mode, the base station mayschedule one or more resources for sidelink communication betweenwireless user devices. The wireless user device (e.g., the Tx UE) maytransmit a PSSCH (e.g., sidelink data channel) through a sidelinkchannel to another wireless user device (e.g., an Rx UE), and mayreceive sidelink HARQ-ACK feedback information about the PSSCH, from theother wireless user device (e.g., the Rx UE) through a PSFCH. If thewireless user device (e.g., Tx UE) is in the base station schedulingmode, the wireless user device (e.g., the Tx UE) may transmit thesidelink HARQ-ACK feedback information received from the other wirelessuser device (e.g., the Rx UE) to a base station (e.g., through an NR Uulink) to inform the base station regarding whether to performretransmission rescheduling. The wireless user device (e.g., the Tx UE)may transmit the corresponding sidelink HARQ-ACK feedback information tothe base station through an NR Uu uplink channel (e.g., PUCCH or PUSCH).

The wireless user device (e.g., the Tx UE) may transmit Channel StatusInformation (CSI) (e.g., HARQ-ACK, CQI, PMI, RI, etc.) on an NR Uu linkthrough the uplink channel of the wireless user device (e.g., the TxUE). For example, the wireless user device (e.g., the Tx UE) maymultiplex sidelink HARQ feedback information with CSI and transmit thesidelink HARQ feedback information multiplexed with CSI (e.g., on the NRUu link). The wireless user device (e.g., the Tx UE) may transmit theCSI on the NR Uu link and the sidelink HARQ feedback informationtogether using the same resource. Accordingly, it may be possible toreduce the number of times the wireless user device reports suchinformation to the base station and to improve the reporting efficiency.For example, if the wireless user device simultaneously reports the CSIon the NR Uu link and the sidelink HARQ feedback information to the basestation through multiplexing, a HARQ codebook for reporting theaforementioned information may need to be determined. One or moremethods for determining the HARQ codebook will be described based on theaforementioned description.

The wireless user device (e.g., an NR V2X Tx UE) may report to the basestation for sidelink HARQ-ACK feedback information about mode 1 sidelinkunicast transmission through an NR Uu (UL). The wireless user device(e.g., the Tx UE) may acquire HARQ feedback information from anotherwireless user device (e.g., the Rx UE) through the PSFCH with respect tosidelink data transmission performed based on a mode 1 resourceallocation method. The wireless user device (e.g., the Tx UE) maymultiplex sidelink HARQ feedback information and Uu HARQ feedbackinformation and simultaneously transmit the sidelink HARQ feedbackinformation and the Uu HARQ feedback information for downlink datatransmission on the NR Uu link through the same physical channel in thesame slot. If the wireless user device (e.g., the Tx UE) transmits HARQfeedback information associated with different links (Uu link/SL link)to the base station through the same physical resource in the same slot,the wireless user device (e.g., the Tx UE) may need to verify amultiplexing method to be applied. Referring to FIG. 9, configurationsof a HARQ codebook operating on an NR Uu link may be classified into atype-1 HARQ codebook scheme (semi-static) and a type-2 codebook scheme(dynamic). A codebook scheme configured for the wireless user device(e.g., the Tx UE) may be configured through RRC signaling from the basestation. The type-1 HARQ codebook (e.g., used on the NR Uu link) mayrefer to a method of configuring a HARQ codebook based on semi-staticparameter configuration. The wireless user device (e.g., the Tx UE) maybe configured with the type-1 HARQ codebook through upper layersignaling from the base station. The type-1 HARQ codebook may beconfigured, for example, based on at least one of: an associated PDSCHtransmission slot timing value that can be transmitted in a singleuplink slot, a PDSCH slot format (slot/non-slot), and/or a subcarrierspacing configuration between a downlink and an uplink. The type-1 HARQcodebook may be configured for a TDD scheme, for example, based on aslot/non-slot for PDSCH reception by further considering a TDD UL-DLconfiguration. However, aspects are not limited thereto.

The type-2 HARQ codebook may refer to a method of configuring a HARQcodebook based on a dynamic indicator (e.g., a downlink assignmentindicator (DAI)) within a PDCCH. The wireless user device (e.g., the TxUE) may be configured with the type-2 HARQ codebook through upper layersignaling from the base station. A method for configuring the type-2HARQ codebook may be a scheme of providing an accumulative/total numberof PDSCH scheduling to the wireless user device (e.g., the Tx UE)through a DAI field within the PDCCH (DCI format 1_0/1_1) indicatingPDSCH scheduling information that can be transmitted in a single uplinkslot. The type-2 HARQ codebook scheme may provide a further efficientcodebook size and composition compared to the type-1 HARQ codebook.

The wireless user device (e.g., the Tx UE) may simultaneously multiplexsidelink HARQ feedback and Uu link feedback information and transmitsidelink HARQ feedback and Uu link feedback information. In determiningthe HARQ codebook, a final NR Uu HARQ codebook may need to be configuredby further considering sidelink HARQ codebook composition.

Referring to FIG. 10, a wireless user device (e.g., Tx UE 1010) mayoperate in an RRC connected mode on a single serving cell. If thewireless user device (e.g., the Tx UE 1010) operates based on mode 1,the wireless user device (e.g., the Tx UE 1010) may perform sidelinkcommunication through resources allocated from a base station (e.g., agNB 1060) for sidelink communication. For example, the wireless userdevice (e.g., the Tx UE 1010) may receive, as a resource allocation forsidelink communication through an NR Uu link from the base station, aspecific NR DCI format (e.g., NR DCI format for SL V2X communication)through a PDCCH. The wireless user device (e.g., the Tx UE 1010) mayperform sidelink communication with another wireless user devices (e.g.,Rx UEs) based on the received information. The wireless user device(e.g., the Tx UE 1010) may perform sidelink communication with the otherwireless user devices (e.g., Rx UEs) based on at least one of unicast,groupcast and broadcast transmissions. The wireless user device (e.g.,the Tx UE 1010) may establish a session with another wireless userdevice (e.g., an Rx UE) for each cast. For example, the base station mayconfigure the respective cast transmissions to have a 1:1 relationshipor an N:1 relationship with a single resource pool in the correspondingwireless user device (e.g., Tx UE 1010). The N:1 relationship mayrepresent that N (one or a plurality of) unicast, groupcast, andbroadcast transmissions are configured to operate in a single resourcepool. For example, referring to FIG. 10, two unicast sessions and twogroupcast sessions may be established in the wireless user device (e.g.,the Tx UE 1010). For example, the wireless user device (e.g., the Tx UE1010) may establish a unicast session with each of other wireless userdevices (e.g., UEs 1020 and 1030). The wireless user device (e.g., theTx UE 1010) may establish a groupcast session with a plurality ofwireless user devices (e.g., UEs 1040-1 and 1040-2). The wireless userdevice (e.g., the Tx UE 1010) may establish a groupcast session withanother plurality of wireless user devices (e.g., UEs 1050-1 and1050-2).

A sidelink HARQ feedback report performed by a wireless user device(e.g., a Tx UE) for a base station may be performed for a datatransmission corresponding to a unicast transmission. For example, thesidelink HARQ feedback report performed by the wireless user device(e.g., the Tx UE) for the base station may be performed for a datatransmission corresponding to unicast and groupcast transmissions. Thewireless user device (e.g., the UE) may report sidelink HARQ feedback tothe base station, for example, based on at least one of: unicast andgroupcast transmissions without performing the sidelink HARQ feedbackreport for a broadcast transmission.

A sidelink data transmission in which the wireless user device (e.g., TxUE) report sidelink HARQ feedback information to the base station isdescribed. In one or more configurations, only the unicast transmissionmay be performed (unicast only). In one or more other configurations,unicast and groupcast transmissions may be performed(unicast+groupcast). In an operation of reporting sidelink HARQ feedbackinformation to the base station, it may be considered only the unicasttransmission or all of the unicast and groupcast transmissions.

A sidelink HARQ codebook may be configured based on an operation ofreporting, by the wireless user device (e.g., the Tx UE), a sidelinkHARQ information bit to the base station in a single uplink slot. Forexample, if the HARQ codebook is configured, the same sidelink HARQinformation bit may be transmitted in a single uplink slot. However, anoccasion relationship corresponding to a single uplink slot may differas shown in the following Table 13. For example, the occasionrelationship may be defined by considering a PSFCH occasion. In one ormore configurations, the occasion relationship may be defined withoutconsidering the PSFCH occasion. Hereinafter, a method of configuring thesidelink HARQ codebook by considering all of the relationships shown inthe following Table 13 will be described.

TABLE 13 PSSCH occasion −> PSFCH occasion −> one UL slot (e.g. onePUCCH) PSSCH occasion −> one UL slot (e.g. one PUCCH)

_Sidelink HARQ codebook may be determined semi-statically, for example,for PUSCCH and/or PUSCH transmissions. For example, a wireless userdevice (e.g., a UE) may be configured with a type-1 HARQ codebook(pdsch-HARQ-ACK-Codebook=semi-static) for HARQ feedback transmissionabout an NR PDSCH transmission. A sidelink HARQ codebook may also beconfigured based on the type-1 HARQ codebook. The wireless user device(e.g., the Tx UE) may be configured with the sidelink HARQ codebookbased on the type-1 HARQ codebook, for example, if the type-1 HARQcodebook (pdsch-HARQ-ACK-Codebook=semi-static) for HARQ feedbacktransmission about an NR PDSCH transmission is configured.

The sidelink HARQ codebook may be defined as an independent sidelinktype-1 codebook (pssch-HARQ-ACK-Codebook=semi-static). For example, thewireless user device (e.g., the Tx UE) may be configured with thesidelink HARQ codebook based on RRC signaling from a base station. Thewireless user device (e.g., the Tx UE) may be configured with thesidelink HARQ codebook through a pre-configuration.

For example, if the wireless user device (e.g., the Tx UE) is configuredwith the independent sidelink codebook type, HARQ codebook combinationsfor a Uu link and a sidelink may be represented by the following Table14. Each of a Uu HARQ codebook and a sidelink HARQ codebook may beconfigured as the type-1 HARQ codebook and the type-2 HARQ codebook andmay be configured based on four cases as show in the following Table 14.

TABLE 14 Uu Type1, SL Type 1 Uu Type1, SL Type 2 Uu Type2, SL Type 1 UuType2, SL Type 2

For example, the type-1 sidelink HARQ codebook may be determined basedon a PSFCH occasion or a PSSCH occasion. The type-1 sidelink HARQcodebook may be determined by considering an active DL BWP, an active ULBWP, and an active SL BWP on a single service cell. The wireless userdevice (e.g., the Tx UE) may determine a PSFCH occasion set associatedwith a single uplink slot (e.g., PUCCH/PUSCH transmission slot). For asidelink HARQ operation, a candidate PSSCH occasion associated with thePSFCH occasion may be pre-configured. The wireless user device (e.g.,the Tx UE) may determine a PSSCH occasion set associated with a singleuplink slot. PSSCH occasions may be regarded/assumed to be associatedwith a single uplink slot. For example, in the case of configuring thetype-1 sidelink HARQ codebook, the wireless user device (e.g., the TxUE) may verify a unicast and/or groupcast session associated with theactive SL BWP and configured in the wireless user device (e.g., the TxUE). The wireless user device (e.g., the Tx UE) may determine whether asidelink feedback transmission is enabled or disabled for each unicastor groupcast session.

For the sidelink HARQ codebook configuration, a number of associatedunicast or groupcast PSSCH occasions (N_(pssch_occasion) ^(psfch)) maybe considered per single PSFCH occasion on the active SL BWP. Theunicast or groupcast PSSCH occasion may be considered to determinewhether a session in which sidelink HARQ feedback is configured on thesidelink is sidelink HARQ ACK or NACK. For example, if the sidelink HARQfeedback is disabled, NACK may be fixed in the sidelink HARQ codebook(e.g., at all times) with respect to a corresponding PSSCH transmission,for example, although the wireless user device (e.g., the Tx UE)performs a sidelink unicast or groupcast PSSCH transmission.

For the sidelink HARQ codebook configuration, one or more PSFCH timeresources may be configured. For example, a PSFCH may be present per Nslots. N may be one of various values. For example, as described abovewith reference 6, N=1, 2, or 4 (or any other number). A minimum time gapmay be determined by considering a processing time of the wireless userdevice (e.g., the UE). PSSCH occasions associated with a single PSFCHtransmission slot and a number thereof may be determined based on aconfiguration about transmission timing correlation between the PSSCHand the PSFCH and signaling. For the sidelink HARQ codebookconfiguration, at least one PSSCH occasion may configure a descending orascending codebook.

Referring to FIG. 11, a case in which at least one PSSCH occasiontransmission is present within a single sidelink slot may be considered.FIG. 11 illustrates an example in which a PSSCH is transmitted based ona non-slot. PSSCH occasions 1120-1, 1120-2, 1120-3, 1120-4, and 1120-5and an associated PSFCH occasion 1110-2 may be present. For the sidelinkHARQ codebook configuration, the PSSCH occasions 1120-1, 1120-2, 1120-3,1120-4, and 1120-5 and a number thereof may be considered. A PSSCHoccasion may correspond to a unicast or groupcast transmission and abroadcast transmission may not consider the PSSCH occasion.

For example, if a wireless user device (e.g., the Tx UE) transmits thePSSCH to another wireless user device (e.g., an Rx UE) based on aunicast session, the wireless user device (e.g., the Tx UE) may transmita single transport block (TB). HARQ feedback information for a singleunicast PSSCH transmission may be 1 bit. For example, a case in whichall of PSSCH occasions corresponding to N_(pssch_occasion) ^(psfch) areunicast PSSCH transmissions may be considered. For example, it may be acase in which sidelink HARQ feedback is enabled. The wireless userdevice (e.g., the Tx UE) may determine a number of sidelink HARQfeedback information bits as many as a number of N_(pssch_occasion)^(psfch). The number of information bits corresponding to the number ofN_(pssch_occasion) ^(psfch) may be required based on each PSSCHtransmission. A case in which the wireless user device (e.g., the Tx UE)performs a PSSCH transmission based on a code block group (CBG) in asidelink may be considered. For example, HARQ feedback may be performedbased on each CBG within a single TB. A number of sidelink HARQ feedbackinformation bits as many as a number of CBGs may be generated. Forexample, the number of sidelink HARQ feedback information bitscorresponding to the number of CBG within a single TB may be generated.For example, if 10 CBGs are included in a single TB, SL HARQ for asingle TB (PSSCH) may include 10 bits for the respective CBGs.

A case in which at least one PSSCH occasion in N_(pssch_occasion)^(psfch) corresponds to a groupcast transmission may be considered. Anoption of reporting sidelink HARQ “ACK/NACK” feedback information may beconfigured. For example, Option 1 may refer to a case in which thewireless user device (e.g., the Tx UE) reports to a base station foronly “NACK” feedback information in sidelink HARQ feedback informationfor the groupcast transmission. The wireless user device (e.g., the TxUE) may report only “NACK” feedback information to the base station byconsidering only a transmission failure. Only NACK may be present insidelink HARQ information. If the wireless user device (e.g., the Tx UE)receives at least NACK on the same PSFCH resource from another wirelessuser device (e.g., one or more of the Rx UEs) within a group, thewireless user device (e.g., the Tx UE) may report NACK to the basestation through an uplink channel. If the wireless user device (e.g.,the Tx UE) does not receive any NACK, the wireless user device (e.g.,the Tx UE) may report ACK through the uplink channel.

Option 2 may refer to a case in which the wireless user device (e.g.,the Tx UE) forwards HARQ ACK/NACK for each PSSCH. For example, in thecase of groupcast PSSCH, a number of sidelink HARQ feedback informationbits as many as a number of Rx wireless user devices (e.g., the Rx UEs)(N_(RX_UE) ^(groupcast)) associated with a groupcast may need to bedetermined. Each of the wireless user devices (e.g., the UEs within agroup) may be identified based on a valid group wireless device ID(e.g., a valid group UE ID) within the group. HARQ feedback informationbit order for a corresponding groupcast transmission may be determinedin descending or ascending order based on an ID value for identifying awireless user device (e.g., a UE) within the corresponding group. For agroupcast PSSCH transmission in Option 1, only a sidelink bit may begenerated. Since the wireless user device (e.g., the Tx UE) transmitsACK/NACK feedback information based on the entire groupcast, only asingle sidelink bit may be required, which may be identical to unicast.For Option 2, each HARQ feedback information bit may be required foreach PSSCH transmission within groupcast and thus, a number of sidelinkHARQ feedback information bits corresponding to the number of Rxwireless user devices (e.g., the Rx UEs) (N_(RX_UE) ^(groupcast)) may berequired.

The type-1 sidelink HARQ codebook may be determined based on a number ofPSFCH occasions (N_(psfch_occasion) ^(pucch)) associated with a singlePUCCH transmission slot on an active UL BWP. Referring to FIG. 12, oneor more PSFCH occasions 1220-1 and 1220-2 may be associated with asingle PUCCH transmission slot 1230. The wireless user device (e.g., theTx UE) may determine a number of available PSFCH occasions(N_(psfch_occasion) ^(pucch)) based on transmittable candidate PSFCHslot timing (e.g., PSFCH occasions 1220-1, 1220-2, and 1220-3). Thetype-1 sidelink HARQ codebook may be configured by considering thenumber of PSFCH occasions (N_(psfch_occasion) ^(pucch)).

The type-1 sidelink HARQ codebook may be determined by considering theSCS ratio (2^(μ) ^(SL) ^(−μ) ^(UL) ) between the sidelink BWP and theuplink BWP. For example, a case in which an SCS value of a sidelink BWPdiffers from that of an uplink BWP may be considered. The followingproposed type-2 sidelink HARQ codebook may be determined by consideringthe SCS ratio between the sidelink BWP and the downlink BWP. Forexample, if sidelink communication is performed based on SL V2X carrieraggregation (CA) or dual-connectivity (DC), the sidelink BWP and theuplink BWP may have different SCS values. For example, if the sidelinkBWP and the uplink BWP have different SCS values, a ratio of the numberof PSFCH/PSSCH occasions associated with a single PUCCH (UL)transmission slot may vary. For example, the ratio may be valid even forthe wireless user device (e.g., the UE) configured with the sidelink V2XCA/DC. A case in which sidelink unicast or groupcast transmission isperformed through a single serving cell (carrier) (SCell) may beconsidered. For example, the wireless user device (e.g., the Tx UE) maytransmit sidelink HARQ feedback information about the aforementionedtransmission to the base station through the uplink channel(PUCCH/PUSCH) on PSCell or PCell that is another serving cell. An SCS ofan uplink BWP of the PCell or PSCell may differ from an SCS of asidelink BWP of a sidelink serving cell. For example, if the SCSs differfrom each other, a number of slots included in a single subframe maydiffer. For example, if a u value of μ value of the above Table 2increases, a number of slots included in a single subframe may increaseand a time length of a single slot may decrease. If a sidelink HARQfeedback transmission is performed through the uplink channel, thewireless user device (e.g., the UE) may consider a slot ratio. If an SCSbetween the sidelink BWP and the uplink BWP is identical at all times,the aforementioned ratio may not be considered to configure the type-1sidelink codebook.

Although a slot timing value is described based on a sidelink, a case ofincluding a downlink/uplink slot may be considered. For example, TDDUL-DL configuration common may be indicated by a System InformationBlock (SIB). The wireless user device (e.g., the Tx UE) may receive anindication of TDD-UL-DL configuration dedicated through RRC signaling.In determining slot timing based on slot information acquired as above,the wireless user device (e.g., the Tx UE) may not considernon-corresponding slot timing to determine the number of occasions.

The wireless user device (e.g., the Tx UE) may determine the type-1 HARQcodebook for transmitting sidelink HARQ feedback information through theuplink channel based on the aforementioned information.

A candidate PSSCH occasion or PSFCH occasion (M_(SL,c)) associated witha single uplink slot (PUCCH or PUSCH) for a single serving cell todetermine the type-1 HARQ codebook may be determined. If the candidatePSSCH occasion or PSFCH occasion (M_(SL,c)) associated with the uplinkslot is determined, a set of slot timing values K_(SL), between a slotassociated with the sidelink BWP and the uplink BWP and the PSSCH/PSFCHoccasion may be considered. For example, K_(SL) may be configured by anupper layer or may be indicated to the wireless user device (e.g., theTx UE) through a pre-configuration. If the aforementioned upper layersignaling is absent, default K_(SL) value (e.g., 1, 2, 3, 4, 5, 6, 7, 8)may be used. Slot timing may be used even for non-slot scheduling.

A scaled TB or CBG within a single PSSCH occasion for determining thetype-1 HARQ codebook may be considered. For example, if transmission isperformed based on the TB, T=1 HARQ bit may be generated for a singlePSSCH occasion, for example, as described above. If transmission isperformed based on the CBG, T=N_(CBG) ^(TB) HARQ bits corresponding to anumber of CBGs configured per a single TB may be generated, for example,as described above.

A cast type and a sidelink feedback option scheduled within a singlePSSCH occasion for determining the type-1 HARQ codebook may beconsidered. For example, in the case of a unicast PSSCH, if sidelinkfeedback is enabled, a number of sidelink feedback information bits maybe T HARQ bits. In the case of a single TB, it may be 1 bit. In the caseof a plurality of CBGs, T HARQ bits may be configured based on a numberof CBGs. For a groupcast PSSCH, if sidelink HARQ feedback is enabled,the number of sidelink information bits may consider a number of Rxwireless user devices (e.g., the Rx UEs). For example, in the case ofthe aforementioned Option 2, a number of HARQ bits corresponding to amultiplication between the T bits and the number of Rx wireless userdevices (e.g., the Rx UEs) may be generated. For the aforementionedOption 1, the number of sidelink information bits may be determined asthe T bits, without considering the number of Rx wireless user devices(e.g., the Rx UEs).

The number of sidelink HARQ feedback information bits for the groupcastPSSCH may be generated as fixed K HARQ bits regardless of a groupcastoption. The SCS ratio between the active sidelink BWP and the activeuplink BWP for determining the type-1 HARQ codebook may be considered.For example, if TDD UL-DL configuration is provided, downlink and uplinkOFDM symbols may be excluded from the PSSCH/PSFCH occasion byconsidering TDD UL-DL configuration. The PSSCH or PSFCH occasion(M_(SL,c)) determined for the serving cell c may sort sidelink HARQinformation bits in descending order/ascending order of the slot timingvalues, for example, as described above.

To configure the type-1 sidelink HARQ codebook, the base station mayprovide additional information related to unicast/groupcast to thewireless user device (e.g., the Tx UE). The base station may allocate aresource for sidelink data transmission to the wireless user device(e.g., the Tx UE) that operates based on mode 1. For example, the basestation may simply allocate only the resource for the sidelink datatransmission and the wireless user device (e.g., the Tx UE) maydetermine for which unicast session or groupcast session the wirelessuser device (e.g., the Tx UE) may perform the sidelink data transmissionusing the allocated resource. The base station may simply indicate aresource to be used for the sidelink and may not clearly verify whetherthe wireless user device (e.g., the Tx UE) has performed the datatransmission for which unicast session or groupcast session on thescheduled resource.

For a groupcast transmission, the wireless user device (e.g., the Tx UE)may receive sidelink HARQ information bits for the groupcasttransmission and may report the corresponding information bits to thebase station. As described above, the base station may be unaware ofwhether the wireless user device (e.g., the Tx UE) has performed PSSCHtransmission for which groupcast session on a specific PSSCH occasion.In the case of unicast, the base station may not be clearly aware of forwhich unicast session the wireless user device (e.g., the Tx UE) hasperformed the PSSCH transmission on a specific PSSCH occasion.

The base station may not be clearly aware of a PSSCH transmissionassociated with a single sidelink HARQ information bit. By consideringthis aspect, the base station may configure at least one of adestination ID field, an SL HARQ process number field, and a new dataindicator (NDI) field within an SL DCI format and may provide sessioninformation for resource scheduling to the mode 1 wireless user device(e.g., the mode 1 Tx UE) through the configured field. The wireless userdevice (e.g., the Tx UE) may schedule an initial transmission or aretransmission for unicast, groupcast, or broadcast based on resourceallocation information and session information received from the basestation. Through this, for which unicast or groupcast session the PSSCHtransmission is performed on the PSSCH occasion may become clear. Inthis manner, an issue regarding HARQ codebook composition may beresolved.

In the case of the groupcast transmission, sidelink HARQ feedback mayallow K HARQ bits to be generated regardless of the sidelink HARQfeedback option (e.g., Option 1 or Option 2). For example, a K value maybe the aforementioned T value. The K value may be a value acquired bymultiplying the T value by the number of Rx wireless user device (e.g.,the Rx UEs). Uncertainty that may occur in the groupcast transmissionmay be removed or reduced. For example, the K value may be configurablethrough RRC signaling.

Referring to FIG. 13, a wireless user device (e.g., the Tx UE) thatoperates based on mode 1 may connect a base station (e.g., gNB) to anRRC connected mode as a serving base station. The wireless user device(e.g., the Tx UE) may operate based on the aforementioned mode 1 forsidelink communication. The wireless user device (e.g., the Tx UE) mayadditionally provide a sidelink V2X service on a licensed carrier onwhich a cellular data service is provided through an NR Uu link. Forexample, based on the aforementioned description, the wireless userdevice (e.g., the Tx UE) may perform HARQ report about a downlink datatransmission (PDCCH/PDSCH) in a specific uplink slot 1330. The wirelessuser device (e.g., the Tx UE) may perform sidelink communication withanother wireless user device (e.g., the Rx UE) based on at least one ofunicast and groupcast transmissions. The wireless user device (e.g., theTx UE) may report to the base station for the sidelink HARQ feedbackreport received from another wireless user device (e.g., an Rx UE). Forexample, as described above, the wireless user device (e.g., the Tx UE)may simultaneously transmit the HARQ feedback about the downlink datatransmission (PDCCH/PDSCH) and the HARQ feedback about the sidelinkthrough multiplexing in the specific uplink slot 1330.

The wireless user device (e.g., the Tx UE) may transmit a PSSCH1 1310-1to another wireless user device (e.g., an Rx UE 0) through a unicastsession 0. The wireless user device (e.g., the Tx UE) may receivesidelink feedback information from the wireless user device (e.g., theRx UE 0) through the PSFCH 1320-1 of slot 1. For example, HARQ feedbackabout the unicast session 0 may be in an enabled state. For example, thewireless user device (e.g., the Tx UE) may transmit a PSSCH2 1310-2 toanother wireless user device (e.g., an Rx UE 1) through a unicastsession 1 and may receive sidelink HARQ feedback information from thewireless user device (e.g., the Rx UE 1) through the PSFCH 1310-2 of theslot 1. Since HARQ feedback about the unicast session 1 may be in adisabled state, the wireless user device (e.g., the Tx UE) may notreceive sidelink HARQ feedback from the wireless user device (e.g., theRx UE 1). The wireless user device (e.g., the Tx UE) may transmit aPSSCH3 1310-3 to other wireless user devices (e.g., an Rx UE 2 and an RxUE 3) through a groupcast session 0 as a single groupcast session. Inthe groupcast session 0, HARQ report may be performed based on theaforementioned HARQ Option 2. Each of the wireless user devices (e.g.,the RX UE 2 and the RX UE 3) may transmit HARQ ACK/NACK to the wirelessuser device (e.g., the Tx UE) through the PSFCH 1320-2 of a slot 3. Thewireless user device (e.g., the Tx UE) may transmit each piece ofsidelink HARQ feedback information to the base station based on a numberof Rx wireless user devices (e.g., the Rx UEs) in the specific uplinkslot 1330.

The wireless user device (e.g., the Tx UE) may transmit a PSSCH4 1310-4to wireless user devices (e.g., an Rx UE 4 and an Rx UE 5) through agroupcast session 1 as another groupcast session. In the groupcastsession 1, HARQ report may be performed based on the aforementioned HARQOption 1. Each of the Rx wireless user devices (e.g., the Rx UE 4 andthe Rx UE 5) may transmit HARQ ACK/NACK to the Tx wireless user device(e.g., the Tx UE) through the PSFCH 1320-2 of the slot 3. If all of theHARQ feedback information received from the Rx wireless user device(e.g., the Rx UEs) is ACK, the Tx wireless user device (e.g., the Tx UE)may transmit HARQ-ACK to the base station as sidelink HARQ feedbackinformation in the specific uplink slot 1330. If even a single piece ofthe HARQ feedback information received from the Rx wireless user device(e.g., the Rx UEs) is NACK, the Tx wireless user device (e.g., the TxUE) may transmit HARQ-NACK to the base station as sidelink HARQ feedbackinformation in the specific uplink slot 1330. For example, all of thegroupcast 0 and the groupcast 1 may be in an enabled state.

The wireless user device (e.g., the Tx UE) may configure a codebook byconsidering the aforementioned situation. For example, the wireless userdevice (e.g., the Tx UE) may determine an associated unicast orgroupcast PSSCH occasion per a single PSFCH occasion on an activesidelink BWP. For example, although description of FIG. 13 is made basedon an example in which a PSSCH is transmitted based on a slot, anon-slot-based transmission may apply as described above. Althoughdescription of FIG. 13 is made based on an example in which a PSSCH istransmitted based on a TB, CBG-based transmission may also apply asdescribed above.

The wireless user device (e.g., the Tx UE) may determine a PSFCHoccasion associated with a single PUCCH transmission slot on an activeuplink BWP. For example, in FIG. 13, two PSFCH occasions 1320-1 and1320-2 may be associated with a single PUCCH transmission slot, forexample, the specific uplink slot 1330. For example, the SCS ratio(2^(μ) ^(SL) ^(−μ) ^(UL) ) between the sidelink BWP and the uplink BWPmay be determined (e.g., a ratio between a sidelink SCS configurationμ_(SL) and an uplink SCS configuration μ_(UL)). For example, althoughthe SCS ratio between the sidelink BWP and the uplink BWP may be 1:1 inFIG. 13, aspects are not limited thereto. As described above, aPSSCH/PSFCH occasion not corresponding to the sidelink based on TDDUL-DL configuration may be excluded. A sidelink codebook may bedetermined based on the aforementioned description. In the case of FIG.13, the sidelink codebook may be determined as shown in FIG. 14. In theunicast 0, HARQ feedback is enabled and only the TB is considered andthus, 1-bit HARQ information may be required. In the unicast 1, HARQfeedback is disabled and thus, HARQ feedback may be NACK and 1-bit HARQinformation may be required. In the groupcast 0, HARQ feedback isreported based on Option 2 and thus, 2-bit HARQ feedback may be requiredbased on the number of Rx wireless user devices (e.g., the Rx UEs). Inthe groupcast 1, only NACK information is reported to the base stationbased on Option 1 and thus, 1-bit HARQ feedback may be required and thesidelink HARQ codebook may include 5 bits. A codebook for sidelink HARQmay be generated and may be finally reported to the base station throughan uplink channel in concatenation with an NR Uu HARQ codebook. Aconcatenation scheme may refer to a scheme of generating a final NR HARQcodebook by attaching the determined sidelink HARQ codebook right afterthe NR Uu HARQ codebook. A plurality of PDSCH occasions and PSSCHoccasions or PSFCH occasions associated with a single UL slot (e.g.,PUCCH/PUSCH Tx slot) may be concatenated between associated HARQ bits intime order.

FIG. 15 illustrates an example of determining a sidelink HARQ codebookby considering a carrier aggregation (CA)/dual connectivity (CD). Forexample, if a wireless user device (e.g., the Tx UE) performs sidelinkcommunication, the wireless user device (e.g., the Tx UE) may performsidelink communication based on at least two serving cells. For example,FIG. 15 illustrates an example in which the wireless user device (e.g.,the Tx UE) is configured with two serving cells (serving cell 0 andserving cell 1). Sidelink HARQ feedback may be configured for eachserving cell. A sidelink HARQ codebook may be configured for eachserving cell based on at least one of a PSSCH/PSFCH occasion, a sidelinkHARQ report option, and a sidelink HARQ enable/disable status for eachserving cell. A final sidelink HARQ codebook may be configured byconcatenating codebooks for the respective serving cells. For example,in FIG. 15, a 5-bit sidelink HARQ codebook may be configured for eachserving cell. The final sidelink HARQ codebook may be configured as a10-bit sidelink HARQ codebook by concatenating the respective sidelinkHARQ codebooks. In the sidelink HARQ codebook, sidelink HARQ feedbackabout a PSSCH transmission associated with each bit may be scheduledbased on a lowest serving cell index. In the sidelink HARQ codebook,subsequent bits may be scheduled based on a subsequent serving cellindex, and such scheduling may end in a highest serving cell index. Inthe sidelink HARQ codebook, sidelink HARQ feedback about a PSSCHtransmission associated with each bit may be scheduled based on ahighest serving cell index. In the sidelink HARQ codebook, subsequentbits may be scheduled based on a subsequent serving cell index, and suchscheduling may end in a lowest serving cell index. The final sidelinkHARQ codebook may be configured based on the sidelink HARQ codebooksconfigured for the respective serving cells.

The wireless user device (e.g., the Tx UE) may map sidelink ACK/NACKinformation based on the configured sidelink HARQ codebook and therebytransmit the same to the base station. If a wireless user device (e.g.,an Rx UE) does not successfully receive a PSSCH transmitted from the Txwireless user device (e.g., the Tx UE) in a state in which HARQ feedbackis enabled, the Rx wireless user device (e.g., the Rx UE) may map NACKfor the corresponding PSSCH transmission and may feedback the same tothe Tx wireless user device (e.g., the Tx UE) through a PSFCH. If the Rxwireless user device (e.g., the Rx UE) successfully receives the PSSCHtransmitted from the Tx wireless user device (e.g., the Tx UE), the Rxwireless user device (e.g., the Rx UE) may map ACK for the correspondingPSSCH transmission and may feedback the same to the Tx wireless userdevice (e.g., the Tx UE) through the PSFCH. For example, if the Rxwireless user device (e.g., the Rx UE) successfully receives the PSSCHtransmitted from the Tx wireless user device (e.g., the Tx UE), the Rxwireless user device (e.g., the Rx UE) may not perform the PSFCHtransmission for the corresponding PSSCH transmission. The Rx wirelessuser device (e.g., the Rx UE) may perform the PSFCH transmission onlyfor NACK. If the PSFCH is not received, the Tx wireless user device(e.g., the Tx UE) may determine that the PSSCH transmission is asuccess. Although sidelink HARQ feedback is in a disabled state, the Txwireless user device (e.g., the Tx UE) may transmit the PSSCH to the Rxwireless user device (e.g., the Rx UE). If the sidelink HARQ feedback isdisabled, a sidelink HARQ bit corresponding to a corresponding PSSCHoccasion may be mapped to NACK (e.g., at all times).

If the Tx wireless user device (e.g., the Tx UE) transmits a PSSCH tothe Rx wireless user device (e.g., the Rx UE) in a state in whichsidelink HARQ feedback is disabled, the Tx wireless user device (e.g.,the Tx UE) may map sidelink HARQ feedback report for the correspondingPSSCH transmission to ACK (e.g., at all times) and may transmit the sameto the base station. If the sidelink HARQ feedback is disabled, the Txwireless user device (e.g., the Tx UE) may map the sidelink HARQfeedback report to a preconfigured state and transmit the same to thebase station.

Since the semi-statically configured type-1 sidelink codebook may bebasically configured based on a PSSCH occasion, there may be a need toconfigure sidelink HARQ feedback for an unscheduled PSSCH occasion. Acorresponding sidelink HARQ bit may be mapped to NACK (e.g., at alltimes). For example, a corresponding sidelink HARQ bit may be mapped toACK (e.g., at all times). Although a sidelink HARQ bit is configured byconsidering the PSSCH occasion, the Tx wireless user device (e.g., theTx UE) may map the sidelink HARQ bit to a pre-configured state andreport the same to the base station since the PSSCH occasion is notscheduled.

As described above with reference to FIG. 15, sidelink HARQ bits may besorted for each cast (unicast/groupcast) session configured in thewireless user device (e.g., the Tx UE) instead of being sorted based ona serving cell index. For example, a sidelink HARQ codebook mayconfigure a sidelink HARQ bit based on a lowest cast index (e.g.,unicast #0). The HARQ codebook may configure a sidelink HARQ bit basedon a lowest PSSCH/PSFCH occasion index in each cast. The sidelink HARQcodebook may configure a sidelink HARQ bit based on a subsequent castindex and may end such sidelink HARQ bit composition in a cast having ahighest index. The sidelink HARQ codebook may configure a sidelink HARQbit based on a highest cast index (e.g., unicast #1). The HARQ codebookmay configure a sidelink HARQ bit based on the lowest (or highest)PSSCH/PSFCH occasion index in each cast. The sidelink HARQ codebook mayconfigure a sidelink HARQ bit based on a subsequent cast index and mayend such sidelink HARQ bit composition in a cast having a lowest index.In this manner, sidelink HARQ bits may be sorted.

FIG. 16 is a flowchart illustrating an example method for reportingsidelink HARQ feedback to a base station based on a sidelink HARQcodebook. Referring to FIG. 16, the Tx wireless user device (e.g., theTx UE) may transmit a PSSCH to at least one Rx wireless user device(e.g., the Rx UE) based on a scheduled PSSCH occasion (S1610). Thewireless user device (e.g., the Tx UE) may refer to a wireless userdevice that performs sidelink communication based on a resourceallocated by the base station based on mode 1. The wireless user device(e.g., the Tx UE) may be aware of session information associated withthe PSSCH transmission based on at least one of SL DCI format,destination ID, sidelink HARQ number, and NDI fields.

The wireless user device (e.g., the Tx UE) may receive sidelink feedbackinformation about the PSSCH transmission from the at least one Rxwireless user device (e.g., the Rx UE) (S1620). The wireless user device(e.g., the Tx UE) may receive sidelink HARQ feedback information througha PSFCH associated with the PSSCH occasion. The wireless user device(e.g., the Tx UE) may receive sidelink HARQ feedback information basedon a cast type. As described above, sidelink HARQ bit information maydiffer depending on whether the sidelink HARQ feedback information issingle TB-based feedback information or CBG-based feedback information.In the case of groupcast, sidelink HARQ bit information may differ basedon a number of Rx wireless user device (e.g., the Rx UEs). For example,in the case of the aforementioned Option 1, if the Tx wireless userdevice (e.g., the Tx UE) receives NACK from at least one Rx wirelessuser device (e.g., the Rx UE), the Tx wireless user device (e.g., the TxUE) may map sidelink HARQ feedback to NACK. The sidelink HARQ feedbackmay include a single bit, which may be similar to unicast. In the caseof the aforementioned Option 2, the Tx wireless user device (e.g., theTx UE) may receive ACK/NACK from each of Rx wireless user device (e.g.,the Rx UEs). As described above, a number of bits for sidelink HARQfeedback may differ based on the number of Rx wireless user device(e.g., the Rx UEs). The wireless user device (e.g., the Tx UE) mayconfigure a sidelink HARQ bit through a sidelink HARQ codebookconfigured based on at least one of a PSSCH/PSFCH occasion associatedwith an uplink slot, a sidelink data transmission type(unicast/groupcast) within the PSSCH occasion, an associated sidelinkHARQ report scheme (Option 1/Option 2), TB/CBG-based sidelinkscheduling, an SCS ratio between active BWPs of different NR/SL links,TDD UL-DL configuration, and a sidelink CA/DC configuration status(S1630). The wireless user device (e.g., the Tx UE) may multiplex theconfigured sidelink HARQ bit and an uplink HARQ bit and transmit thesame to the base station (S1640). As described above, the sidelink HARQcodebook may be configured to be concatenated with the uplink HARQcodebook.

FIG. 27 illustrates an example of a case in which a wireless user devicerequires a necessary SL HARQ-ACK state determining method in a specificsituation.

Referring to the example of FIG. 27, a base station (e.g., a gNB)transmits two PDCCHs (SL grants) to the wireless user device (e.g., theTx UE) for SL transmission resource scheduling of a first PSCCH/PSSCH(RX UE #1, Unicast #1) and a second PSCCH/PSSCH (Rx UE #2, Unicast #2).A Tx resource pool configured in the corresponding wireless user device(e.g., the Tx UE) may refer to a resource pool configured with PSFCHresources. In FIG. 27, the corresponding Tx resource pool is configuredsuch tat that a PSFCH occasion may be present per two slots. Each ofPSCCH/PSSCH transmission slots scheduled through the two PDCCHs has asingle associated PSFCH occasion as described above. SL HARQ-ACKinformation received by the corresponding wireless user device (e.g.,the Tx UE) from an Rx wireless user device (e.g., an Rx UE) is reportedto the base station (e.g., the gNB) through an uplink (Uu link)PUCCH/PUSCH transmission. A codebook (e.g., a number of SL HARQ-ACK bitscommonly understood by a base station and the Tx wireless user device)configured for SL HARQ feedback to be transmitted on the PUCCH/PUSCHcorresponds to a type-1 codebook (i.e., semi-static codebook). Asdiscussed above, the type-1 codebook may provide configuration regardingPSFCH occasions associated with a single PUCCH transmission through RRCsignaling and a size of the SL HARQ-ACK codebook to report SL HARQfeedback to the base station is determined based on the configuration.For example, referring to FIG. 27, with the assumption that two PSFCHoccasions 2710 are associated with a single PUCCH transmission 2720 andit is configured through the RRC signaling, the type-1 codebook isconfigured using two SL HARQ-ACK bits corresponding to the respectivePSFCH occasions and the two SL HARQ-ACK bits may be reported to the basestation through the PUCCH (or PUSCH) transmission. SL transmissionresources indicated through the received PDCCHs (SL grants) may be usedto perform SL data (PSCCH/PSSCH) transmission through two different Rxwireless user devices (e.g., Rx UEs) or differentunicast/groupcast/broadcast transmissions based on SL schedulingdetermination of the wireless user device (e.g., the Tx UE). While thefirst PSCCH/PSSCH transmission 2730 is performed with respect to SL HARQfeedback enabled Rx UE/radio bearer/cast type, the second PSCCH/PSSCHtransmission 2740 may be performed with respect to SL HARQ feedbackdisabled Rx UE/radio bearer/cast type (e.g., SL HARQ feedback disabledunicast/groupcast or broadcast not requiring SL HARQ feedback). Thewireless user device (e.g., the Tx UE) expects SL HARQ feedbackreception from the Rx wireless user device (e.g., Rx UE), for example,only with respect to the first PSCCH/PSSCH transmission, and may notexpect SL HARQ feedback reception from the Rx wireless user device(e.g., Rx UE) associated the second PSCCH/PSSCH transmission. This isbecause SL feedback is disabled or SL feedback is not required withrespect to the UE/radio bearer/cast type corresponding to the secondtransmission. The wireless user device (e.g., the Tx UE) does not expectPSFCH reception in the second PSFCH occasion associated with the secondPSCCH/PSSCH transmission. Since the PSFCH is not received, the wirelessuser device (e.g., Tx UE) may determine an SL HARQ-ACK state for thecorresponding PSFCH occasion as “NACK” at all times and may report thesame to the base station through a PUCCH. Such Tx wireless user device(e.g., Tx UE) operation may cause an erroneous misalignment and/or anincorrect indication that the Tx wireless user device (e.g., Tx UE)requests the base station to retransmit resources for the secondPSCCH/PSSCH transmission. This is because the base station is unaware ofwhether data is transmitted to actual SL HARQ feedback enabled RxUE/bearer/cast type with respect to the second transmission resource. Ifthe Tx wireless user device (e.g., Tx UE) reports NACK to the basestation as above, transmission of SL data that is transmitted to the SLHARQ feedback enabled Rx wireless user device (e.g., RX UE) may beincorrectly indicated as a failure. As a result, the Tx wireless userdevice (e.g., Tx UE) may additionally perform unnecessary PDCCHtransmission (SL grant for retransmission) for retransmission of thebase station. To resolve the above issue, if the Tx wireless user device(e.g., Tx UE) needs to report SL HARQ feedback to the base station withrespect to the above case (e.g., the PSCCH/PSSCH transmission for whichSL HARQ feedback is disabled or SL HARQ feedback is not required, suchas broadcast transmission), an SL HARQ-ACK state corresponding to thecorresponding PSFCH occasion may be allocated as “ACK” at all times andthe wireless user device (e.g., Tx UE) may report the same to the basestation. In this manner, the base station may avoid additional PDCCHscheduling for retransmission of the PSCCH/PSSCH and may avoidunnecessary system overhead and operation associated PDCCH reception ofthe wireless user device (e.g., UE) accordingly.

Dynamic SL HARQ codebook may be configured. The sidelink HARQ codebookmay be configured based on dynamic signaling. For example, the codebookconfigured based on dynamic signaling may be a type-2 sidelink codebook.For example, if an NR Uu type-2 HARQ codebook(pdsch-HARQ-ACK-Codebook=dynamic) is configured, the sidelink HARQcodebook may also be configured as a type-2 sidelink HARQ codebook. A Txwireless user device (e.g., a Tx UE) may configure the sidelink HARQcodebook based on dynamic signaling and may transmit the configuredsidelink HARQ codebook to a base station through an uplink channel. Forexample, the base station may define/determine a sidelink codebookcomposition configuration (pssch-HARQ-ACK-Codebook=dynamic) and mayallow the wireless user device (e.g., the Tx UE) to operate based on theaforementioned type-2 sidelink HARQ codebook, for example, based on RRCsignaling or a pre-configuration.

If the wireless user device (e.g., the Tx UE) is configured with thetype-2 sidelink HARQ codebook, the wireless user device (e.g., the TxUE) may determine PDCCH occasions (for PDSCH or PDSCH SPS releasescheduling) and PSSCH occasions associated with a single uplink slot(PUCCH transmission slot) based on related timing values, for an activeDL BWP, an active UL BWP, and an active SL BWP on a single serving cell.Available candidate sets may be configured based on a configurationabout timing relationship between the PSSCH/PSFCH occasion and the ULslot (PUCCH/PUSCH) of the aforementioned semi-static SL HARQ codebookdetermination.

For the aforementioned semi-static SL HARQ codebook determination, theHARQ codebook may be statically configured by considering availablecandidate PSSCH/PSFCH occasions, and a size of the sidelink HARQcodebook may be predetermined and all of the Tx wireless user device(e.g., the Tx UE) and the base station may verify clear information. Forthe aforementioned semi-static SL HARQ codebook determination, anunnecessary sidelink HARQ feedback bit may be set, which may cause aninefficient sidelink HARQ codebook size. A method for configuring thesidelink HARQ codebook based on dynamic signaling is described byconsidering the above aspect.

The HARQ codebook for (e.g., actually) scheduled PDSCH or PDSCH SPSrelease may be configured through a downlink assignment indicator (DAI)field within a PDCCH in association with NR Uu. By considering this, thesidelink HARQ codebook may be configured by defining/determining asidelink assignment indicator (SAI) field within an SL DCI format.

For example, only a counter SAI may be defined in the SL DCI format. Anaccumulative number of sidelink PDCCH monitoring occasions (e.g., whereunicast or groupcast PSSCH transmissions are scheduled, up to a currentPDCCH monitoring occasion including each SL DCI) may be indicated basedon the counter SAI. For example, a total SAI may be defined/determined.For example, the total SAI may indicate a total number of unicast orgroupcast PSSCH scheduling, scheduled up to a current sidelink PDCCHmonitoring occasion.

A candidate PSSCH or PSFCH occasion (M_(SL,c)) associated with a singleuplink slot (PUCCH or PUSCH) for a serving cell c may be determined.Slot timing values between a UL slot associated with the sidelinkBWP/uplink BWP and the PSSCH/PSFCH occasion may be a set of K_(SL). Forexample, K_(SL), may be configured by the upper layer or may beindicated to the wireless user device (e.g., the UE) through apre-configuration. If there is no upper layer signaling orpre-configuration, default K_(SL) may be used. For example, defaultK_(SL) may be “{1, 2, 3, 4, 5, 6, 7, 8}”. Default K_SL may have largervarious timing values than the above values. Slot timing may beavailable for non-slot scheduling. A slot timing value may apply basedon a non-slot structure. The wireless user device (e.g., the Tx UE) mayreceive the SL DCI format through SL DCI. The SL DCI format may includeCounter-SAI (C-SAI) or Counter-DSAI (C-DSAI). The SL DCI format mayinclude Total-SAI (T-SAI) or Total-DSAI (T-DSAI). Similar to theaforementioned semi-static SL HARQ codebook determination, TB orCBG-based scheduling may be performed within a single PSCCH occasion.For example, if TB-based scheduling is performed, a number of sidelinkHARQ feedback information bits may be 1 bit (T=1 HARQ bit) byconsidering only a single TB. If CBG-based scheduling is performed, anumber of sidelink HARQ feedback information bits may be T bits(T=N_(CBG) ^(TB) HARQ bits) based on a number N_(CBG) ^(TB) of CBGsconfigured per a TB. A cast type and sidelink HARQ feedback optionscheduled within a single PSSCH occasion may be considered. In the caseof a unicast PSSCH and sidelink HARQ feedback enabled, the number ofsidelink HARQ feedback information bits may be T bits. In the case ofthe aforementioned Option 2 corresponding to a groupcast PSSCH andsidelink HARQ feedback enabled, the number of sidelink HARQ feedbackinformation bits may be determined through a multiplication of the Tbits and the number of Rx wireless user devices (e.g., the Rx UEs)(T×R_UE HARQ bits). In the case of the aforementioned Option 1corresponding to the groupcast PSSCH and sidelink HARQ feedback enabled,the number of sidelink HARQ feedback information bits may be the T bits.On PSSCH or PSFCH occasions (M_(SL,c)) determined for the serving cellc, sidelink HARQ feedback information bits may be sorted in(ascending/descending) order of C-SAI or C-DSAI values. If anotherserving cell is configured based on CA/DC, sidelink HARQ feedbackinformation bits may be sorted even or subsequent another serving cellbased on the aforementioned method.

If a Counter_Sidelink assignment indicator (C_SAI) value indicatedthrough a C_SAI field value within the SL DCI format increases by 1, thesidelink HARQ codebook may be differently determined. The sidelink HARQcodebook may be differently configured through dynamic signaling. If aC_SAI value increases by 1, a sidelink HARQ codebook bit may change. Forexample, if sidelink DCI scheduling for unicast PSSCH (HARQ enable) orgroupcast PSSCH (HARQ Option 1 enable) is provided with a C_SAI value,the Tx wireless user device (e.g., the Tx UE) may determine thatsidelink HARQ feedback information corresponds to T bits. For example,if TB-based scheduling is performed within the PSSCH occasion, a numberof sidelink HARQ feedback information bits may be 1 bit. If CBG-basedscheduling is performed within the PSSCH occasion, a number of sidelinkHARQ feedback information bits may be T bits based on a number of CBGs.The sidelink HARQ codebook may be generated by a number of added bits.

If SL DCI scheduling for groupcast PSSCH (HARQ Option 2 enable) isprovided with a C_SAI value, the Tx wireless user device (e.g., the TxUE) may generate sidelink HARQ bit information based on the number of RxUEs within a group. For example, if the groupcast PSSCH is based on aCBG, the number of sidelink HARQ feedback information bits may begenerated by a value acquired by multiplying the number of Rx wirelessuser devices (e.g., the Rx UEs), for example, by the number of CBGs perTB (Rx UE×CBG per TB).

Referring to FIG. 17, a C_SAI value may be additionally indicated basedon dynamic signaling with respect to C_DAI for a downlink BWP. C_DAI andC_SAI may be separated and indicated. In a sidelink HARQ codebook,sidelink HARQ feedback information bits may be sorted based on theaforementioned C_SAI. A Tx wireless user device (e.g., the Tx UE) maytransmit a PSSCH to an Rx wireless user device (e.g., an Rx UE) based ona PDCCH monitoring occasion included in SL DCI. The wireless user device(e.g., the Tx UE) may receive sidelink feedback information about thecorresponding PSSCH from the Rx wireless user device (e.g., the Rx UE)through a PSFCH 1710-1. The SL DCI may include the aforementioned C_SAI,and sidelink HARQ feedback information bits may vary in the sidelinkcodebook based on C_SAI. If the same C_SAI value is scheduled for the Txwireless user device (e.g., the Tx UE), the Tx wireless user device(e.g., the Tx UE) may configure different sidelink codebooks based on acast type of sidelink HARQ and a sidelink HARQ option of thecorresponding cast type. For example, referring to part (a) of FIG. 18,all of C_SAI values may be associated with a unicast transmission type,and sidelink HARQ bits corresponding to T bits may be sorted for therespective SAI values. For example, as described above, a number ofsidelink HARQ bits may be 1 bit based on a TB and may be T bits based ona CBG. If two TB transmissions are allowed (configured) even in a PSSCH,such as NR Uu, the number of sidelink HARQ feedback information bits maybe associated with 2 bits every time a single SAI value increases. TheNR Uu may be configured by an upper layer such that two TB s aretransmitted for a single PDSCH on a corresponding serving cell. Everytime a single C_DAI value increases, 2 NR Uu HARQ bits may beassociated.

Part (b) of FIG. 18 illustrates a case in which the groupcasttransmission is configured and the sidelink HARQ feedback option is 2.If a groupcast PSSCH transmission including C_SAI=3 is scheduled for theTx wireless user device (e.g., the Tx UE), the number of sidelink HARQfeedback information bits corresponding to the number of Rx wirelessuser devices (e.g., the Rx UEs) within the corresponding group may beassociated with a single SAI value. Part (c) of FIG. 18 illustrates acase in which the groupcast transmission is configured and the sidelinkHARQ feedback option is 1. If the groupcast PSSCH transmission includingC_SAI=3 is scheduled for the Tx wireless user device (e.g., the Tx UE),a single sidelink HARQ feedback bit may be associated with a SAI value.In the case of sidelink HARQ feedback Option 2, the Tx wireless userdevice (e.g., the Tx UE) may receive sidelink HARQ information bits forthe respective wireless user devices from the Rx wireless user devices(e.g., the Rx UEs) through independent PSFCH resources, respectively.The wireless user device (e.g., the Tx UE) may report the same to thebase station through the uplink channel and may assist the base stationwith determining a scheduling method for retransmission. In the case ofsidelink HARQ feedback Option 1, a single sidelink HARQ feedbackinformation bit may be associated per C_SAI, which may be similar to theunicast transmission.

If PSSCH SPS transmission is present on a timing occasion associatedwith the uplink slot, it may be allocated at the end of a HARQ codebookdetermined based on DAI/SAI. For example, if PDSCH SPS is present on thecorresponding occasion with the PSSCH SPS, they may be mapped at the endof a Uu HARQ codebook and SL HARQ codebook determined based on the DAIand the SAI, respectively. If at least one SPS transmission isperformed, all of the at least one SPS transmission may be arranged atthe end of the HARQ codebook and the first received SPS may be allocatedin order from the back. HARQ information bits for the PDSCH SPS and thePSSCH SPS may be mapped, for example, after the Uu HARQ codebook and theSL HARQ codebook determined based on the DAI and the SAI.

FIG. 19 illustrates an example method for configuring a sidelinkcodebook by considering a sidelink multicarrier (CA/DC). If sidelinkcommunication is performed based on a multicarrier, a T_SAI value may beindicated with C_SAI per each PDDCH monitoring occasion. The T_SAI valuemay indicate a total accumulative number of PSSCH scheduling up to acurrent PDCCH monitoring occasion. The T_SAI value may indicate arefreshed value per each PDCCH occasion. Referring to FIG. 19, althoughsidelink communication is performed based on the multicarrier, sidelinkHARQ feedback information may be reported to a base station in an uplinkslot associated with PSFCH occasions 1910-1 and 1910-2, for example, asdescribed above. A C_SAI value may apply alike in the same or similarmanner as the aforementioned sidelink HARQ bit sorting manner. A C_SAIvalue may be determined based on a serving cell index. For example, theC_SAI value may be determined in ascending order from a low serving cellindex to a high serving cell index (or in descending order). The C_SAIvalue may be determined by another method. In FIG. 19, the C_SAI valuemay be 1 in a PDCCH monitoring occasion 1930-1 for serving cell 0 andthe C_SAI value may be 2 in a PDCCH monitoring occasion 1930-2 forserving cell 1. The C_SAI value of the serving cell 0 may be 3 in aPDCCH monitoring occasion 1930-3 for subsequent serving cell 0 and theC_SAI value of the serving cell 1 may be 4 in a PDCCH monitoringoccasion 1930-4 for subsequent serving cell 1. The T_SAI value may be atotal SAI value in a corresponding PDCCH monitoring occasion. In thefirst PDCCH monitoring occasions 1930-1 and 1930-2 for the respectiveserving cells 0 and 1, the T_SAI value may be 2. In the PDCCH monitoringoccasions 1930-3 and 1930-4 for the subsequent other serving cells 0 and1, the T_SAI value may be 4.

Table 15 may show a C_SAI value and a T_SAI value within a sidelink DCIformat. For example, a SAI value may be defined as shown in Table 15 asa 2-bit field within the SL DCI format. In Table 15, a K value mayindicate an accumulative SAI (C-SAI) or total SAI (T-SAI) value ofreceived SL DCI in a serving cell and a PDCCH monitoring occasion (forSL DCI). The C-SAI value may indicate an accumulative number of sidelinkscheduling up to a specific PDCCH monitoring occasion. In the case ofsidelink CA (or DC), the C-SAI value may indicate an accumulative numberof sidelink scheduling in a frequency domain (e.g., a serving cellindex) within the same PDCCH monitoring occasion. As described above,the T_SAI value may indicate a total number of sidelink scheduling up tothe specific PDCCH monitoring occasion.

Referring to FIG. 20, a sidelink HARQ feedback information bit may beassociated with a sidelink HARQ feedback information bit determined byconsidering at least one of a sidelink HARQ option and a cast type perC_SAI. As described above, if PSSCH SPS transmission is present on atiming occasion associated with the uplink slot, it may be allocated atthe end of a HARQ codebook determined based on DAI/SAI.

TABLE 15 Number of serving cells, PDCCH monitoring occasions in whichSPS PSSCH release indicated by SAI V_(C-SAI) ^(SL) or PDCCH or PSSCHtransmisson associated with SL MSB, LSB V_(T-SAI) ^(SL) DCI (PDCCH) inpresent (K and K ≥ 1) 0, 0 1 (K − 1)mod4 + 1 = 1 0, 1 2 (K − 1)mod4 + 1= 2 1, 0 3 (K − 1)mod4 + 1 = 3 1, 1 4 (K − 1)mod4 + 1 = 4

Referring to FIG. 21, C_DAI and C_SAI may be integrally counted in asingle serving cell. Referring to part (a) of FIG. 21, a Tx wirelessuser device (e.g., the Tx UE) configured with mode 1 may perform anuplink HARQ transmission by defining, in each of a DCI format and an SLDCI format, a Counter_Downlink and sidelink assignment indicator(C_DSAI) field as a common field with respect to scheduling allocationcorresponding to PDSCH/PDSCH SPS release on a Uu link and schedulingallocation corresponding to unicast or groupcast (HARQ enable)PSSCH/PSSCH SPS release on a sidelink. Downlink HARQ feedbackcomposition and sidelink HARQ feedback composition may be accumulativelycounted by the same value. Referring to part (b) of FIG. 21, ifC_DSAI=1, a sidelink HARQ feedback information bit may be configured. IfC_DSAI=2, downlink HARQ feedback information bits may be configured. Asdescribed above, counting may be performed using the same value, and thesidelink HARQ feedback information bit and the downlink HARQ feedbackinformation bits may be alternately present (e.g., which differs fromconfigurations shown in FIGS. 18 and 20). If SPS transmission is presentin a timing occasion associated with the uplink slot, it may beallocated at the end of a HARQ codebook determined based on DAI/SAI.

Only a number of scheduling for PSSCH transmission may not be counted todefine a K value in the above Table 15. The K value may be acquired byintegrally counting PDSCH/PDCCH indicating PDSCH SPS release andPSSCH/PDCCH indicating PSSCH SPS release for each serving cell and PDCCHmonitoring occasion and may be used to perform sidelink HARQ bitordering. As described above, Uu HARQ and SL HARQ feedback informationbits may be discontinuously allocated and thereby transmitted to thebase station.

FIG. 22 illustrates a case in which C_DAI and C_SAI are integrallycounted in a single serving cell based on a sidelink multicarrier.Referring to FIG. 22, a Tx wireless user device (e.g., the Tx UE)configured with mode 1 may perform an uplink HARQ transmission bydefining, in each of a DCI format and an SL DCI format, a C_DSAI fieldas a common field with respect to scheduling allocation corresponding toPDSCH/PDSCH SPS release on a Uu link and scheduling allocationcorresponding to unicast or groupcast (HARQ enable) PSSCH/PSSCH SPSrelease on a sidelink. If the sidelink operates based on themulticarrier, a Total Downlink and sidelink assignment indicator (TDSAI) field may be defined in each of the DCI format and the SL DCIformat.

A case in which an SCS of an active DL BWP and an SCS of an active SLBWP differ from each other may be considered. Referring to FIGS. 23 and24, a time length of a PDCCH monitoring occasion for SL and a timelength of a PDCCH monitoring occasion for DL may differ from each other.C_SAI, D_SAI and C_DSAI values may increase starting from an occasionthat is located first in time and other operations are described above.Referring to parts (a) and (b) of FIG. 23, a C_SAI value and a D_SAIvalue may be separated from each other and may be separately counted.Referring to FIG. 24, a C_SAI value and a D_SAI value may be integratedand used as a single C_DSAI value. The C_DSAI value may be counted basedon an occasion that is located first in time in a PDCCH monitoringoccasion for SL and a PDCCH monitoring occasion for DL.

FIG. 25 is a flowchart illustrating an example of a method of reporting,by a wireless user device, sidelink HARQ feedback to a base stationbased on a sidelink HARQ codebook. Referring to FIG. 25, the Tx wirelessuser device (e.g., the Tx UE) may transmit a PSSCH to at least one Rxwireless user device (e.g., the Rx UE) based on a scheduled PSSCHoccasion (S2510). The wireless user device (e.g., the Tx UE) may referto a wireless user device that performs sidelink communication based ona resource allocated from the base station based on mode 1. The wirelessuser device (e.g., the Tx UE) may receive sidelink feedback informationabout the PSSCH transmission from the at least one Rx wireless userdevice (e.g., the Rx UE) (S2520). The wireless user device (e.g., the TxUE) may receive sidelink HARQ feedback information through a PSFCHassociated with the PSSCH occasion. The wireless user device (e.g., theTx UE) may receive sidelink HARQ feedback information based on a casttype. Sidelink HARQ bit information may differ depending on whethersidelink HARQ feedback information is single TB-based feedbackinformation or CBG-based feedback information. The sidelink HARQ bitinformation may differ based on TB/CBG-based sidelink scheduling, theSCS ratio between active BWPs of different NR/SL links, TDD UL-DLconfiguration, and sidelink CA/DC configuration status. In the case ofgroupcast, the sidelink HARQ bit information may differ based on anumber of Rx wireless user devices (e.g., the Rx UEs) or a predeterminedfixed value. For the aforementioned Option 1, if the Tx wireless userdevice (e.g., the Tx UE) receives NACK from at least one Rx wirelessuser device (e.g., an Rx UE), the Tx wireless user device (e.g., the TxUE) may map sidelink HARQ feedback to NACK. The sidelink HARQ feedbackmay include a single bit, which is similar to unicast. For theaforementioned Option 2, the Tx wireless user device (e.g., the Tx UE)may receive ACK/NACK from each of Rx wireless user devices (e.g., the RxUEs). Regardless of the options, in the case of groupcast, the sidelinkHARQ bit information may be generated based on a fixed K bit value atall times. A number of bits for sidelink HARQ feedback may differ basedon the number of Rx wireless user device (e.g., the Rx UEs) or the fixedvalue. The wireless user device (e.g., the Tx UE) may configure asidelink HARQ bit through a sidelink HARQ codebook dynamicallyconfigured based on at least one of a C_SAI value, a T_SAI value, and aDSAI (C_DSAI, T DSAI) value that is a combination of SAI and DAI(S2530). The C_SAI value may indicate an accumulative number of unicastor groupcast PSSCH scheduling allocations up to a current sidelink PDCCHmonitoring occasion, including each SL DCI. The T_SAI value may beconfigured by considering a sidelink multicarrier. The sidelink HARQcodebook may add a number of sidelink HARQ feedback information bits byconsidering a scheduled PSSCH every time the C_SAI value increases. Forexample, the T_SAI value may be provided to the Tx wireless user device(e.g., the Tx UE) by refreshing a total accumulative number of PSSCHscheduling up to a current PDCCH occasion, per a PDCCH occasion. Thewireless user device (e.g., the Tx UE) may multiplex the configuredsidelink HARQ bit and uplink HARQ bit and transmit the same to the basestation (S2540).

FIG. 26 illustrates a base station device and a terminal device (e.g., awireless user device, a UE, etc.). Referring to FIG. 26, a base stationdevice 2600 may include a processor 2620, an antenna device 2612, atransceiver 2614, and a memory 2616.

The processor 2620 may perform baseband related signal processing andmay include an upper layer processing 2630 and a physical (PHY) layerprocessing 2640. The upper layer processing 2630 may process anoperation of a Medium Access Control (MAC) layer, a Radio ResourceControl (RRC) layer, or more upper layers. The PHY layer processing 2640may process an operation (e.g., uplink received signal processing anddownlink transmission signal processing) of a PHY layer. The processor2620 may perform the overall operation of the base station device 2600in addition to performing baseband related signal processing.

The antenna device 2612 may include at least one PHY antenna. If theantenna device 2612 includes a plurality of antennas, Multiple InputMultiple Output (MIMO) transmission and reception may be supported. Thetransceiver 2614 may include a radio frequency (RF) transmitter and anRF receiver. The memory 2616 may include operation processed informationof the processor 2620, software associated with an operation of the basestation device 2600, an operating system (OS), an application, etc., andmay include a component, for example, a buffer.

The processor 2620 of the base station device 2600 may be configured toimplement an operation of a base station described herein. The terminaldevice 2650 may include a processor 2670, an antenna device 2662, atransceiver 2664, and a memory 2666. Communication between the terminaldevices 2650 may be performed based on sidelink communication. Eachterminal device 2650 performing sidelink communication may refer to adevice that performs sidelink communication with another terminal device2650 in addition to the base station device 2600.

The processor 2670 may perform baseband-related signal processing andmay include an upper layer processing 2680 and a PHY layer processing2690. The upper layer processing 2680 may process an operation of a MAClayer, an RRC layer, or more upper layers. The PHY layer processing 2690may process an operation (e.g., downlink received signal processing anduplink transmission signal processing) of a PHY layer. The processor2670 may control the overall operation of the terminal device 2650 inaddition to performing baseband-related signal processing.

The antenna device 2662 may include at least one PHY antenna. If theantenna device 2662 includes a plurality of antennas, MIMO transmissionand reception may be supported. The transceiver 2664 may include an RFtransmitter and an RF receiver. The memory 2666 may store operationprocessed information of the processor 2670, software associated with anoperation of the terminal device 2650, an OS, an application, etc., andmay include a component, for example, a buffer. The processor 2670 ofthe terminal device 2650 may be configured to implement an operation ofa wireless user device described herein.

The processor 2620 of the base station 2600 may transmit, via RRCsignaling, configuration information to the terminal device (e.g., awireless user device). The configuration information may compriseinformation required to transmit sidelink HARQ feedback information tothe base station 2600. The processor 2620 of the base station device2600 may indicate to a terminal device one or plural uplink slotconfiguration information associated with a PSFCH occasion. Theprocessor 2620 of the base station device 2600 may transmit SL DCI tothe terminal device. The SL DCI may include at least one of a C_SAIvalue and a C_DSAI value.

The processor 2670 of the terminal device 2650 may transmit a PSSCH toat least one another terminal device based on a scheduled PSSCHoccasion. The processor 2670 of the terminal device 2650 may receivefeedback information about the PSSCH transmission from the at least oneother terminal device. The processor 2670 of the terminal device 2650may configure a sidelink HARQ bit through a sidelink HARQ codebookconfigured based on at least one of a PSSCH/PSFCH occasion associatedwith an uplink slot, a sidelink data transmission type within the PSSCHoccasion, and an associated sidelink HARQ report scheme. The processor2670 of the terminal device 2650 may multiplex the configured sidelinkHARQ bit and uplink HARQ bit and transmit the same to the base stationdevice 2600.

The processor 2670 of the terminal device 2650 may transmit the PSSCH toat least one another terminal device based on the scheduled PSSCHoccasion. The processor 2670 of the terminal device 2650 may receivefeedback information about the PSSCH transmission from the at least oneother terminal device. The processor 2670 of the terminal device 2650may configure a sidelink HARQ bit through a sidelink HARQ codebookdynamically configured based on the C_SAI value. The processor 2670 ofthe terminal device 2650 may multiplex the configured sidelink HARQ bitand uplink HARQ bit and transmit the same to the base station device2600.

In addition to the feature described above, the base station and thewireless user device may implement one or more features describedhereinafter. The base station may transmit to the wireless user device,one or more radio resource control (RRC) signals indicating one or moreparameters associated with sidelink communication between wireless userdevices. The sidelink communication may be configured as semi-staticsidelink configuration (e.g., type 1 SL HARQ codebook). The one or moreparameters may comprise a set of slot timing values (e.g., {1, 2, 3, 4,5, 6, 7, 8}). The base station may transmit sidelink downlink controlinformation (SL DCI) comprising a first indicator field that indicates asidelink hybrid automatic repeat request (HARQ) feedback timing. A valueof the first indicator field may comprise one of the set of slot timingvalues. The wireless user device may transmit, based on the SL DCI, toone or more second wireless user devices, a plurality of sidelinksignals via a first quantity of sidelink channel resources (e.g., afirst quantity of sidelink channel occasions, such as PSCCH occasionsand PSSCH occasions). The wireless user device may receive, during afirst time interval and from the one or more second wireless userdevices, first sidelink HARQ feedback information responsive to theplurality of sidelink signals. The wireless user device may determine,based on the sidelink HARQ feedback timing and based on the first timeinterval, a second time interval to transmit the first sidelink HARQfeedback information to the base station. The wireless user device maydetermine, based on the first quantity, a sidelink HARQ codebook (e.g.,a size of the sidelink HARQ codebook). The wireless user device maytransmit, during the second time interval and based on the sidelink HARQcodebook and to the base station, an uplink signal indicating the firstsidelink HARQ feedback information.

The base station may transmit, to the wireless user device, second SLDCI comprising a second indicator field that indicates a second sidelinkHARQ feedback timing. A value of the second SL DCI may comprise anotherone of the set of slot timing values. The wireless user device maytransmit, based on the second SL DCI, a plurality of second sidelinksignals via a second quantity of second sidelink channel resources. Theplurality of second sidelink signals may be transmitted to the one ormore second wireless user devices or any other wireless user devices.The wireless user device may receive, during a third time interval,second sidelink HARQ feedback information responsive to the plurality ofsecond sidelink signals. The wireless user device may determine, basedon the second sidelink HARQ feedback timing and based on the third timeinterval, the second time interval to transmit the second sidelink HARQfeedback information. The determining the sidelink HARQ codebook (e.g.,the size of the sidelink HARQ codebook) may be further based on thesecond quantity. The uplink signal may further indicate the secondsidelink HARQ feedback information. The first sidelink HARQ feedbackinformation and the second sidelink HARQ feedback information may bemultiplexed in the uplink signal. A value of the first indicator fieldmay correspond to a slot timing value between the first time intervaland the second time interval. The first time interval may correspond toa physical sidelink feedback channel (PSFCH) occasion and the secondtime interval may correspond to a physical uplink control channel(PUCCH) slot. The one or more parameters may indicate information of aset of slot timing values, K_(SL). Each slot timing value may indicate atiming between a physical sidelink feedback channel (PSFCH) occasion anda physical uplink control channel (PUCCH) slot. The PUCCH slot maycomprise the second time interval. The determining the sidelink HARQcodebook may comprise determining, based on the set of slot timingvalues, K_(SL), the sidelink HARQ codebook (e.g., the size of thesidelink HARQ codebook). The determining the sidelink HARQ codebook maycomprise determining, based on a ratio between a sidelink subcarrierspacing (SCS) configuration and an uplink SCS configuration, thesidelink HARQ codebook (e.g., the size of the sidelink HARQ codebook).The determining the sidelink HARQ codebook may comprise determining,based on a time resource associated with a physical sidelink feedbackchannel (PSFCH) (e.g., a period of a PSFCH time resource), the sidelinkHARQ codebook (e.g., the size of the sidelink HARQ codebook). Thewireless user device may sort, based on a descending order of slottiming values indicated by the one or more parameters, sidelink HARQfeedback information bits, and may generate, based on the sorting, theuplink signal. The first time interval may correspond to a physicalsidelink feedback channel (PSFCH) reception slot. The second timeinterval may correspond to an uplink slot (e.g., a PUCCH slot) or a slotcomprising one or more uplink symbols. The determining the sidelink HARQcodebook may comprise determining, based on a quantity of physicalsidelink feedback channel (PSFCH) occasions associated with the uplinksignal, the sidelink HARQ codebook (e.g., the size of the sidelink HARQcodebook). The plurality of sidelink signals may comprise a firstsidelink signal transmitted to a wireless user device for which asidelink HARQ feedback is disabled. The wireless user device maydetermine, based on determining that the sidelink HARQ feedback isdisabled for the wireless user device and based on determining that aretransmission of a sidelink channel (e.g., a PSSCH and/or a PSCCH) isnot required, a positive acknowledgment for the first sidelink signal.The wireless user device may determine a positive acknowledgementassociated with a scheduled sidelink channel resource of the firstquantity of sidelink channel resources. The wireless user device may nottransmit a sideilnk signal via the scheduled sidelink channel resource.

The base station may transmit, to the wireless user device, sidelinkdownlink control information (SL DCI) associated with transmission ofone or more sidelink signals. The wireless user device may transmit,based on the SL DCI and to one or more second wireless user devices, theone or more sidelink signals via a first quantity of sidelink channelresources. The wireless user device may receive, during a first timeinterval and from the one or more second wireless user devices, firstsidelink HARQ feedback information responsive to the one or moresidelink signals. The wireless user device may determine, based on asidelink HARQ feedback timing and based on the first time interval, asecond time interval to transmit the first sidelink HARQ feedbackinformation. The wireless user device may determine, based on the firstquantity, a sidelink HARQ codebook (e.g., the size of the sidelink HARQcodebook). The wireless user device may transmit, during the second timeinterval, based on the sidelink HARQ codebook, and to the base station,an uplink signal indicating the first sidelink HARQ feedbackinformation.

The base station may transmit, to the wireless user device, one or moreradio resource control (RRC) signals indicating one or more parametersassociated with sidelink communication between wireless user devices.The one or more parameter may comprise information of a set of slottiming values, K_(SL). The SL DCI may comprise a first indicator fieldthat comprises one of the set of slot timing values, K_(SL), to indicatethe sidelink HARQ feedback timing. The base station may transmit, to thewireless user device, second SL DCI associated with transmission of oneor more second sidelink signals. The second SL DCI may comprise a secondindicator field that indicates a second sidelink HARQ feedback timing.The wireless user device may transmit, based on the second SL DCI, oneor more second sidelink signals via a second quantity of second sidelinkchannel resources. The wireless user device may receive, during a thirdtime interval, second sidelink HARQ feedback information responsive tothe one or more second sidelink signals. The wireless user device maydetermine, based on the second sidelink HARQ feedback timing and basedon the third time interval, the second time interval to transmit thesecond sidelink HARQ feedback information. The determining the sidelinkHARQ codebook may be further based on the second quantity. The uplinksignal may further indicate the second sidelink HARQ feedbackinformation. The determining the sidelink HARQ codebook may comprisedetermining, based on a quantity of physical sidelink feedback channel(PSFCH) occasions associated with the uplink signal, a size of thesidelink HARQ codebook (e.g., the size of the sidelink HARQ codebook).The one or more sidelink signals may comprise a first sidelink signaltransmitted to a wireless user device for which a sidelink HARQ feedbackis disabled. The wireless user device may determine, based ondetermining that the sidelink HARQ feedback is disabled for the wirelessuser device and based on determining that a retransmission of a sidelinkchannel (e.g., a PSSCH and/or a PSCCH) is not required, a positiveacknowledgment for the first sidelink signal. The wireless user devicemay determine a positive acknowledgement associated with a scheduledsidelink channel resource of the first quantity of sidelink channelresources. The wireless user device may not transmit a sideilnk signalvia the scheduled sidelink channel resource.

The base station may transmit to the wireless user device, one or moreradio resource control (RRC) signals indicating one or more parametersassociated with sidelink communication between wireless user devices.The sidelink communication may be configured as dynamic sidelinkconfiguration (e.g., type 2 SL HARQ codebook). The one or moreparameters may comprise a set of slot timing values (e.g., {1, 2, 3, 4,5, 6, 7, 8}). The base station may transmit first sidelink downlinkcontrol information (SL DCI) comprising a first indicator field thatindicates a sidelink hybrid automatic repeat request (HARQ) feedbacktiming and first counter SAI indicating a first value (e.g., 1). Thebase station may transmit second SL DCI comprising a second indicatorfield that indicates a second HARQ feedback timing and second counterSAI indicating a second value (e.g., 2). The base station may transmitthird SL DCI comprising a third indicator field that indicates a thirdHARQ feedback timing and third counter SAI indicating a third value(e.g., 3). One or more additional SL DCI may be transmitted by the basestation to the wireless user device by incrementing the counter SAIvalue of the one or more additional SL DCI (e.g., by one). The values ofthe first indicator field, the second indicator field, and the thirdindicator field may comprise one of the set of slot timing values. Thewireless user device may transmit, based on the first SL DCI, to one ormore second wireless user devices, a first sidelink signal via a firstsidelink channel resource (e.g., a first sidelink channel occasion, suchas a PSCCH occasion and a PSSCH occasion). The wireless user device maytransmit, based on the second SL DCI, to one or more second wirelessuser devices, a second sidelink signal via a second sidelink channelresource (e.g., a second sidelink channel occasion, such as a PSCCHoccasion and a PSSCH occasion). The wireless user device may receive,during a first time interval (e.g., a first PSFCH occasion) and from oneor more second wireless user devices, first sidelink HARQ feedbackinformation responsive to the first and second sidelink signals. Theassociation between the first sidelink channel resource and the firstPSFCH occasion may be determined, for example, based on the first SLDCI. The association between the first sidelink channel resource and thefirst PSFCH occasion may be determined, for example, based on aconfiguration of a PSFCH time resource (e.g., a PSFCH time resourceperiod) and a scheduled location of the first sidelink channel resource(e.g., a first PSSCH occasion). The association between the secondsidelink channel resource and the first PSFCH occasion may bedetermined, for example, based on the second SL DCI. The associationbetween the second sidelink channel resource and the first PSFCHoccasion may be determined, for example, based on a configuration of aPSFCH time resource (e.g., a PSFCH time resource period) and a scheduledlocation of the second sidelink channel resource (e.g., a second PSSCHoccasion). The wireless user device may transmit, to one or more secondwireless user devices, a third sidelink signal via a third sidelinkchannel resource (e.g., a third sidelink channel occasion). The thirdsidelink signal may be a sidelink signal based on SPS (e.g., PSSCH SPS).The sidelink signal based on SPS may be configured by one or more RRCmessages, and DCI activating one or more PSSCH SPS transmissions may betransmitted from the base station to the wireless user device. Upon theSPS activation, a plurality of PSSCH SPS may be transmitted periodicallyvia a plurality of PSSCH occasions. The wireless user device maytransmit, based on the third SL DCI, to one or more second wireless userdevices, a fourth sidelink signal via a fourth sidelink channel resource(e.g., a fourth sidelink channel occasion, such as a PSCCH occasion anda PSSCH occasion). The wireless user device may receive, during a secondtime interval (e.g., a second PSFCH occasion) and from one or moresecond wireless user devices, second sidelink HARQ feedback informationresponsive to the third and fourth sidelink signals. The associationbetween the third sidelink channel resource and the second PSFCHoccasion may be determined, for example, based on an RRC messageconfiguring one or more PSSCH SPS occasions and a configuration of aPSFCH time resource (e.g., a PSFCH time resource period). Theassociation between the fourth sidelink channel resource and the secondPSFCH occasion may be determined, for example, based on the third SLDCI. The association between the fourth sidelink channel resource andthe second PSFCH occasion may be determined, for example, based on aconfiguration of a PSFCH time resource (e.g., a PSFCH time resourceperiod) and a scheduled location of the fourth sidelink channel resource(e.g., a fourth PSSCH occasion). The first HARQ feedback timingindicates a timing between the first PSFCH occasion and a third timeinterval (e.g., a PUCCH slot). The second HARQ feedback timing indicatesa timing between the first PSFCH occasion and the third time interval.The third HARQ feedback timing indicates a timing between the secondPSFCH occasion and the third time interval.

The wireless user device may determine, based on the first, second,third sidelink HARQ feedback timings and based on the first timeinterval and the second time interval, the third time interval totransmit sidelink HARQ feedback information indicating the firstsidelink HARQ feedback information and the second sidelink HARQ feedbackinformation to the base station. The wireless user device may determine,based on the quantity of the sidelink channel occasions associated withthe third interval, a sidelink HARQ codebook (e.g., a size of thesidelink HARQ codebook). The size of the sidelink HARQ codebook may bedetermined based on the total counter SAI value (e.g., 3). The size ofthe sidelink HARQ codebook may be incremented by one, for example, if anACK/NACK for the PSSCH SPS is reported. The wireless user device maydetermine the size of the HARQ codebook (e.g., 3+1=4). The sidelink HARQACK/NACK bits may be sorted, for example, based on lower counter SAIvalue or higher slot timing value, (e.g., the K_(SL) value). Thewireless user device may transmit, during the third time interval andbased on the sidelink HARQ codebook and to the base station, an uplinksignal indicating the first sidelink HARQ feedback information and thesecond sidelink HARQ feedback information. The SAI field in each of thefirst, second, third SL DCI may include a 2-bit value. The value may bedetermined based on the examples described herein (e.g., Table 15). Thewireless user device may determine one or more PSFCH occasionsassociated with a PUCCH slot in which HARQ feedback information istransmitted to the base station. The wireless user device may determineone or more PSSCH occasions associated with a PSFCH occasion. Thewireless user device may determine a PDCCH occasion associated with aPSSCH occasion. SL DCI indicating a PSSCH transmission in the PSSCHoccasion may be transmitted via the PDCCH occasion.

This disclosure is provided to enable any person skilled in the art topractice the various aspects described herein. Various modifications tothese aspects will be readily apparent to those skilled in the art, andthe generic principles defined herein may be applied to other aspects.Thus, the claims are not intended to be limited to the aspects literallydescribed herein but are to be accorded the full scope consistent withthe language of the claims. All structural and functional equivalents tothe elements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims.

What is claimed is:
 1. A method comprising: receiving, by a wirelessuser device from a base station, one or more radio resource control(RRC) signals indicating one or more parameters associated with sidelinkcommunication between wireless user devices; receiving, from the basestation, sidelink downlink control information (SL DCI) comprising afirst indicator field that indicates a sidelink hybrid automatic repeatrequest (HARQ) feedback timing; based on the SL DCI, transmitting, toone or more second wireless user devices, a plurality of sidelinksignals via a first quantity of sidelink channel resources; during afirst time interval, receiving, from the one or more second wirelessuser devices, first sidelink HARQ feedback information responsive to theplurality of sidelink signals; determining, based on the sidelink HARQfeedback timing and based on the first time interval, a second timeinterval; determining, based on the first quantity, a sidelink HARQcodebook; and during the second time interval and based on the sidelinkHARQ codebook, transmitting, to the base station, an uplink signalindicating the first sidelink HARQ feedback information.
 2. The methodof claim 1, further comprising: receiving, from the base station, secondSL DCI comprising a second indicator field that indicates a secondsidelink HARQ feedback timing; based on the second SL DCI, transmittinga plurality of second sidelink signals via a second quantity of secondsidelink channel resources; during a third time interval, receivingsecond sidelink HARQ feedback information responsive to the plurality ofsecond sidelink signals; and determining, based on the second sidelinkHARQ feedback timing and based on the third time interval, the secondtime interval to transmit the second sidelink HARQ feedback information,wherein the determining the sidelink HARQ codebook is further based onthe second quantity, and wherein the uplink signal further indicates thesecond sidelink HARQ feedback information.
 3. The method of claim 2,wherein the first sidelink HARQ feedback information and the secondsidelink HARQ feedback information are multiplexed in the uplink signal.4. The method of claim 1, wherein a value of the first indicator fieldcorresponds to a slot timing value between the first time interval andthe second time interval, and wherein the first time intervalcorresponds to a physical sidelink feedback channel (PSFCH) occasion andthe second time interval corresponds to a physical uplink controlchannel (PUCCH) slot.
 5. The method of claim 1, wherein the one or moreparameters indicates information of a set of slot timing values, K_(SL),wherein each slot timing value indicates a timing between a physicalsidelink feedback channel (PSFCH) occasion and a physical uplink controlchannel (PUCCH) slot, and wherein the PUCCH slot comprises the secondtime interval.
 6. The method of claim 5, wherein the determining thesidelink HARQ codebook comprises determining, based on the set of slottiming values, K_(SL), the sidelink HARQ codebook.
 7. The method ofclaim 1, wherein the determining the sidelink HARQ codebook comprisesdetermining, based on a ratio between a sidelink subcarrier spacing(SCS) configuration and an uplink SCS configuration, the sidelink HARQcodebook.
 8. The method of claim 1, wherein the determining the sidelinkHARQ codebook comprises determining, based on a period of a physicalsidelink feedback channel (PSFCH) time resource, the sidelink HARQcodebook.
 9. The method of claim 1, further comprising: based on adescending order of slot timing values indicated by the one or moreparameters, sorting sidelink HARQ feedback information bits; andgenerating, based on the sorting, the uplink signal.
 10. The method ofclaim 1, wherein: the first time interval corresponds to a physicalsidelink feedback channel (PSFCH) reception slot; and the second timeinterval corresponds to an uplink slot or a slot comprising one or moreuplink symbols.
 11. The method of claim 1, wherein the determining thesidelink HARQ codebook comprises determining, based on a quantity ofphysical sidelink feedback channel (PSFCH) occasions associated with theuplink signal, the sidelink HARQ codebook.
 12. The method of claim 1,wherein the plurality of sidelink signals comprise a first sidelinksignal transmitted to a wireless user device for which a sidelink HARQfeedback is disabled, and wherein the method further comprises: based onthe sidelink HARQ feedback being disabled for the wireless user deviceand based on a retransmission of a sidelink channel being not required,determining a positive acknowledgment for the first sidelink signal. 13.The method of claim 1, further comprising: determining a positiveacknowledgement associated with a scheduled sidelink channel resource ofthe first quantity of sidelink channel resources, wherein the wirelessuser device does not transmit a sidelink signal via the scheduledsidelink channel resource.
 14. A method comprising: receiving, by awireless user device from a base station, sidelink downlink controlinformation (SL DCI) associated with transmission of one or moresidelink signals; based on the SL DCI, transmitting, to one or moresecond wireless user devices, the one or more sidelink signals via afirst quantity of sidelink channel resources; during a first timeinterval, receiving, from the one or more second wireless user devices,first sidelink HARQ feedback information responsive to the one or moresidelink signals; determining, based on a sidelink HARQ feedback timingand based on the first time interval, a second time interval;determining, based on the first quantity, a sidelink HARQ codebook; andduring the second time interval and based on the sidelink HARQ codebook,transmitting, to the base station, an uplink signal indicating the firstsidelink HARQ feedback information.
 15. The method of claim 14, furthercomprising receiving, from the base station, one or more radio resourcecontrol (RRC) signals indicating one or more parameters associated withsidelink communication between wireless user devices, wherein the one ormore parameter comprises information of a set of slot timing values,K_(SL), and wherein the SL DCI comprises a first indicator field thatcomprises one of the set of slot timing values, K_(SL), to indicate thesidelink HARQ feedback timing.
 16. The method of claim 14, furthercomprising: receiving, from the base station, second SL DCI associatedwith transmission of one or more second sidelink signals, wherein thesecond SL DCI comprises a second indicator field that indicates a secondsidelink HARQ feedback timing; and based on the second SL DCI,transmitting one or more second sidelink signals via a second quantityof second sidelink channel resources.
 17. The method of claim 16,further comprising: during a third time interval, receiving secondsidelink HARQ feedback information responsive to the one or more secondsidelink signals; and determining, based on the second sidelink HARQfeedback timing and based on the third time interval, the second timeinterval to transmit the second sidelink HARQ feedback information,wherein the determining the sidelink HARQ codebook is further based onthe second quantity, and wherein the uplink signal further indicates thesecond sidelink HARQ feedback information.
 18. The method of claim 14,wherein the determining the sidelink HARQ codebook comprisesdetermining, based on a quantity of physical sidelink feedback channel(PSFCH) occasions associated with the uplink signal, a size of thesidelink HARQ codebook.
 19. The method of claim 14, wherein the one ormore sidelink signals comprise a first sidelink signal transmitted to awireless user device for which a sidelink HARQ feedback is disabled, andwherein the method further comprises: based on the sidelink HARQfeedback being disabled for the wireless user device and based on aretransmission of a sidelink channel being not required, determining apositive acknowledgment for the first sidelink signal.
 20. The method ofclaim 14, further comprising: determining a positive acknowledgementassociated with a scheduled sidelink channel resource of the firstquantity of sidelink channel resources, wherein the wireless user devicedoes not transmit a sideilnk signal via the scheduled sidelink channelresource.